I need some help with a book I'm writing....

She has a 5 year old son so that is one reason to stay.

Having children is not reason to stay in an abusive relationship. In fact it's on of the best reasons to get out of one.

By staying in the relationship, it implies to the child that it's okay for one parent to abuse the other. Second, it increases the chances that the child will grow up with the same bad habits of one of the parents, either the abuser or the abused.

I completely, completely agree with this statement!!

I know it doesn't help the OP with her story dilemma, but it's such an important thing for people to know. Staying together for the kids, staying in a bad relationship for the kids...its the worst thing you can ever do.

I was brought up by two amazing people who did NOT belong together, but stayed together "for the kids." All it taught me was not to believe in marriage, and to get the idea, via osmosis, that your own happiness should be subjugated for someone else's, and that it is ok to waste a life being unhappy if you think you are helping someone else.

Would you really want your kid to live like that? Is that really the message you want to send?

Again, apologies to the OP for hacking this. Just needs to be said more often!!

Have you already fully developed the male character and the whole story? If yes, don't read on and ignore this comment.

If not: she may have fallen in love with him because he used to be different, a nice, strong, reliable character. He may have changed because of an illness, for example a brain tumour. That could also be a reason why she's staying with him, because she knows that it's not really HE who is so abusive, but it's because of the tumour changing him.

Great idea! It sounds like your character is younger but dementia does it to.

are you nicholas sparks?

Maybe she's afraid she wouldn't be able to support her son and herself on her own or end up in the street. Maybe she thinks they can work on his problems and things would get better. Maybe she doesn't want her son to grow up without a dad. Maybe she's worried he might turn violent if she leaves him.
Probably that man isn't evil and it's not black and white since life doesn't go that way - he's a man with some serious issues who is sometimes hurtful and, probably, sometimes compassionate, like people are. I think that in order to understand why she stays, you have to first work on his character and make sure he's complex and that you can use many more words to describe him rather than "abusive". Why does he act the way he does? What's his background and what lead him down this road? Is he aware that what he's doing is hurtful, does he want or try to change? I think all those things will get you closer.

Good luck, I hope this helped.