Abuse is a great leveller and has no prejudices at all. It can happen to anyone at any time.
As a family lawyer I see it every day. parent/child; child/parent: man/woman; woman/man: man/man; woman/woman: black/white; white/black:
Any combination, any age, any time.
As has rightly been said above it is often insidious and begins as general 'putting down' robbing the person of their self esteem and self respect so that by the time the physical stuff starts the person has nowhere else to go, does not believe they can live without the other person and half the time is convinced that the abuse is their fault.
I have acted for people who have left their abuser time after time. The police stop taking action, people stop listening. They've heard it all before. The spiral gets deeper and deeper and then gets passed on to the next generation. It's tragic.
It is very important to get the message out that people who are abused, raped, assaulted etc ARE NOT WEAK. They are not bad people and they are not failures. Like everyone else on the planet they have made some bad choices and it is NEVER TOO LATE to make good ones. Speak to as many people as you can and let them know what's going on... families, friends, counsellors, doctors.... anyone who can help in any way, even if it is only to give evidence later on that you have told people about it.
If you are in the uk there is a law called the Protection From Harassment Act which makes it illegal for anyone to act in such a way as it puts another person in fear for their safety or in such a way as it threatens, harasses or pesters another person. This is the so called 'stalker' legislation. It is also a criminal offence to assault someone (an assault can be as simple as a push or even a slap on the shoulder), threaten to kill someone, put one or more people in fear for their safety, incite hatred towards someone becuase of their race, colour or sexual orientation.....
The point is the legislation is there. THe police often don't want to do anything about it and will even tell people that there is nothing they CAN do but this is because so many people in relationship situations back out before it goes anywhere. (By the way if you make a statement to the police about any criminal offence they can proceed to prosecute even if you later withdraw the statement). However, if pressed they have to.
If the police won't or can't help then go see a solicitor and get and injunction / restraining order.
More than anything believe in yourself and that it is NEVER ok for anyone, no matter who they are to make you feel worthless or abuse you physically or emotionally. It is NEVER your fault.
Oops sorry... slipped into rant mode.