What to do if battered in a domestic relationship?

1) Leave - in all violent situations retreat is the smart move. Even the marines if attacked will attempt immediately to retreat and regroup.
2) Battered women shelters are places of safety and readily available. Use them if family members and friends homes aren't available.  If you are a man who has been battered leave too.  There are no battered men's shelters that I know of, despite their need, so go to a friends or family or get a hotel for a night.
3) Speak to the police.  Speaking to the police does not require lodging a complaint immediately. The police are a great source of information.  Ask them about your rights and what they recommend.  Sadly the police work on a 'first come first serve' basis, something criminals commonly know, if a complaint is being lodged.   Not speaking to the police might cause you to be considered the 'victimizer' if the other person came forward first as the 'victim'.  That said, policewomen with the Vancouver Police Department and the RCMP have with some of the cases I know personally demonstrated great insight and sensitivity.  At different times a local policewoman has further done clinics and programs training women in prevention of violence.  These programs have been outstanding and extremely helpful.  Men are often treated poorly by younger police or older police. It's been a real hit or miss with men who were attacked being ridiculed on one occasion while encountering extremely understanding and helpful police officers on other occasions.  So mostly the police are these days really enlightened to the complexity and dynamics of domestic violence and whatever criticism that they may have somewhat deserved in the past is mostly historic today.  If need be lay charges and get a 'restraining order'.  However before making this decision realize that this may simply 'deal' with the 'immediate problem without addressing the bigger or broader issues.  Ensure safety but beware of knee jerk reactions made in the heat of the moment.
4) Talk to a lawyer who specializes in domestic violence.  Go early rather than late.  Lawyers are especially helpful knowing individuals rights and can address the immediate problem and the broader and farther reaching aspects of any decision. That's what they are specifically trained in.  In the past they were 'divorce advocates' and quite reasonably criticized as a principal cause of the failure of marriages and the rise of the 'legal lottery' of divorce with divorces lawyers vying with criminal lawyers for spotlights and high wages. This is not the case in Canada now that there is a balance of power in gender in the courts, more female judges and far fewer of those old dinosaurs  cro magnums who as men 'wanted to help the wee woman' or felt 'a woman should know her place' or that first group of angry radical feminists who thought all men should be castrated or 'pink women' deserved their fate.  The great books about these divorce courts will read like Jerry Springer shows in years to come with the gross insaniety and cultural bias and extraordinary costs to families and communities of those wild years of penalizing married people while rewarding singles and players by default. That era is ending and mediation and better trained judges all have resulted in lawyers being a good place to turn when there is domestic violence. A number of male lawyers specifically specialize locally in dealing with men married to violent angry dangerous women just as there have been very good female lawyers locally who have specialized in helping women married to psychopathic wife beaters.
5) See your family doctor. The person who sees most everyone and has a pivotal role in the community is the family physician.  His training is specific to addressing domestic violence and often especially if older and more experience he or she will be a source of sage wisdom.
6) See a psychiatrist. Often people who are experiencing domestic violence whether male or female are suffering depression, anxiety and even post traumatic stress disorder.  Psychiatrists are highly trained and experienced in domestic violence. If children are involved ask to see a Pediatric Psychiatrist as these specifically are trained in family and children in crisis.  Unfortunately some psychiatrists today are only trained in psychopharmacology and one should avoid seeing such a limitted psychiatrist.  That said the majority of psychiatrists are still trained in biopsychosocial approaches and some are even trained specifically in family and marriage therapy.
7) Clinical psychologists - psychologists who have phd's and 2 years of specific training with humans do excellent work in cases of domestic violence if they don't carry a predjudice against men or women.  Unfortunately a lot of psychologists have had extreme gender bias to the point of being grossly sexist without any awareness because they do not have to be trained in 'transference' and 'counter transference' issues to be a simple psychologists or psychological counsellor.  Psychiatrists and clinical psychologists and those trained in marriage, system and family therapy are specifically trained to drop their natural bias against men or women based on their child of origin.
8) Beware of counsellors. Individually they are 'comforting' but domestic violence is one of the most complex of human problems and commonly counsellors with only 6 months or a year or two of clinical training commonly say things like 'you should divorce' and routinely 'believe' the 'story' the man or woman tells and acts on the 'screen play' rather than waiting to learn the 'real story'.  Counsellors like to rescue and give advise like girlfriends and boyfriends and like to 'feel good' themselves as the person who 'knows what to do'. They rarely have been trained to sit in the shit and muddle of human relationships experiencing the pain and realizing that more often than not what is presented as an 'acute' 'emergency' has been going on a life time or more.  I rarely see counsellors finding out who all the actual players in the domestic drama are unless their 'counselling' was predated with training as a social worker or occupational therapist or pastoral counsellor.
9) Don't buy a gun.  Don't go on the computer looking for a list of effective poisons. Don't hire a hit man.  Revenge is best served cold.  In the heat of the moment whatever you do is likely to get you in jail or worse.  A "love" is not worth dying over. Hollywood has kindly showed us that great passions and great loves can occur more than once. Romeo and Juliet was a play about teen agers.  For an adolescent everything is the end of the world.
10) Avoid homicide or suicide. They are the wrong answer.
11) If you meet a guy or girl and they seem lovely and everything goes well and then you get whacked, you probably are a 'victim'. Healthy people recognise that the 'car' they bought is a 'lemon' and trade it in quick.  Unhealthy people try to fix it up. Don't try to fix it up alone.  Wiring problems aren't easy to solve. They are deceptively easy but they're notoriously complex.  Get expert help.
12) Relationships are best treated by people who are in committed relationships and trained in relationship therapy and are seeing the couple together.
13) If domestic violence arises after a year or two of relationship the domestic violence is intrinsic to the individual and the relationship.  Both or all three need to be fixed.
14) Anger management courses for men and women are extremely benefical and effective.
15) If a person keeps picking bad apples they are no longer a 'victim' they are a 'volunteer'.  Alright predators look for such victims but one is bad luck 2 in this field is definitely a pattern. This is reason for in depth and often longer term individual therapy.
16) If the violence occurs around drugs and alcohol get treatment specific for drugs and alcohol.  All addiction specialists know that stop the drugs and alcohol especially as part of a treatment program and the tendency to violence evaporates after a year or two of being clean and sober.
17) Beware of the friend or therapist with 'glib' advice.  If someone is 'threatening' the 'threat' may well be real.  Don't just 'leave' thinking that you'll be 'safe'.  I've called 911 on three occasions when the police did have 'cars' because a riot or some other emergency was taking place when I was dealing with violence or a break in.  One person I know was promised "a new identity' like on television if they did something against a big league criminal in a domestic violence scenario. The trouble was the funding fell through.  I've know people who switched countries and were hunted down.  People who have never been threatened themselves often have all the 'textbook' answers.  It's good to ask people if they themselves have ever experienced domestic violence, violence, or being involved with courts, counsellors and psychiatrists.  People who have ball caps and t shirts in the field are far better than new grads in these areas.  Young people want to look good especially bearocrats and they may be wanting to impress their boss whereas for you it may be life and death. There are no free lunches so ask them what's in it for them and specifically ask if they've had any real experience or are you their 'guinea pig". I know people have to learn but preferrably you don't want to be their 'test' case.
18) As a marriage therapist I have specifically recommended people separate for a specific amount of time for a specific reason with specific tasks to perform. In one case the woman used this time to get her ducks in a row to take the house and kids when her part in the violence was equal and her lover was not her husband. I've seen the same thing done by men.  Given that 'possession is 90%" of the law' departure for any more than weeks at most is not something I like to recommend if the house is a major portion of the combined assets.  I think counsellors, psychologists and psychiatrists should advise patients to seek advise from lawyers in these instances so that people know what the law is any day of a given week.  Predators female or male always seem to be up on the law just like criminals. The innoscent don't think they need to be only to commonly find themselves victimized in the courts after being victimized in the bed room
19) Beware of talking to the female friends who agree and say what a asswipe the boyfriend or husband is. They commonly are feeling smug and superior to you and getting their rocks off living off your being a loser. These people usually watch soap operas and can't believe their good fortune having a friend whose such a fool to talk to them and might end up on Jerry Springer. Similarly men should avoid talking to friend who say their wife is a ho.  Commonly that "friend" is the first one to try and get her in bed after you break up.  Family are good but naturally they should take your side.  They are not unbiased. In primitive cultures not uncommonly marital problems and relationship problems weren't the domain of parents but rather that of aunts uncles and and older brothers and older sisters.  These people have a different slant on the relationship and often provide good insight a parent can't.
20) 1/4 of couples polled had violence. The most common violence I've seen in my practice has been the "Bickerson's", two people who tend to get physical and outsiders only here about it when it goes over the top.  I do see a lot of violence in those people with drugs and alcohol and it evaporates with treatment. I 've certainly seen violent individuals with schizophrenia or bipolar though this is relatively rare.  But in the home a chronically depressed, perpetually grieving, drama queen or personality disorder often violence is just under the service.
21) As I get older I don't like having unstable emotional or dramatic people in my home. It's a bit like my parents not liking arguments at the table when they were eating. My home is a 'safe place ' and people should ensure their place is safe and avoid having potentially violent people inside. I see potentially violent people in public. One of my female friends is a woman who hasn't benefitted much from divorce and anger management but she's highly entertaining in the coffeeshop where her stories are often hilarious.  A friend who went to jail for violence is a good guy sober, to go fishing with. I don't think I'd want to sleep in the same building with either.  I wouldn't sleep well in the room with somebody else's pit bull either.