There are 2 specific issues and 1 general issue that I see here.

Don't Let Her Keep Hurting You

The first specific issue is your wife. Obviously a big issue. Ok, she was abused. We can understand why she's behaving like the Witch of the East. But just because we understand why she does bad things, does that condone her doing those things? I don't think just because you understand why she is hurting you, that you should continue allowing her to hurt you. It would be better to help her, perhaps by getting her into a therapist's office and locking her in there so she doesn't mess up someone else's life, like your child.

Get a Lawyer

The second specific issue is you. Wassup with you? There are nurturers. There are enablers. And there are doormats. Where do you fit in? Listen bud, you should be seething by now, with your trust in this women completely ruined. I know I wouldn't be asking the question "is it worth staying". I'd be asking, "where's the best lawyer", and "how can I get total custody of my child".

You Might Have Issues

For you not to be asking these questions is bad, and if you do get into any other relationship, I wonder if you would pick the same kind of partner. Hey, get yourself over to a therapist and start asking questions pertaining to your own self. If I was to guess, I'd be guessing that you came from chaos yourself, and have issues in your background to deal with.

Lastly is the general issue of "unconditional love". I do not belive in it. Ok, except for agape, and some religions have messed that up so badly that they can't even have real fun with the opposite sex.

What Will It Take For You To Let Go?

At what point does love die? If your wife had been in bed with someone and you walked in? If she had shown you videotapes? If she physically abused you? If she hurt your child? Is there anything that she could have done that would have made the love you felt for her die? I believe there's just gotta be some kind of breaking point. Otherwise love becomes trivial because it's only a one-way thing.

Lefty