I beat my girlfriend, how do I stop blaming myself?

my (ex) girlfriend was a very beautiful very intelligent manipulative girl with serious issues.. boulimic.. cuts herself.. drug abuser.. sucky childhood and she likes to play with men.. she totally drove me crazy, one day she would tell me she wants to marry me and the other she would say I'm a loser, I'm not good enough for her and she wants to use her looks to find a rich man.. she earns her money by dating sugar daddies.. she says she doesn't have with them but it hard to believe she gets 10 grand to stay for a weekend in paris and nothing happens... she confessed to her best friend that she really loves me but she loves making me crazy too.. once I punched a hole in her door.. now i found out she loved that.. it makes her feel powerful.. I just can't understand why.. I did EVERYTHING for her.. she would call me in the middle of the night.. crying bcuz of her boulimia and I would come over to help her, no matter when or where I was always there. She destroyed my life, tore me and my family and friends apart on purpose. she would make up stories just to get me mad. The other day she got me so mad that I just grabbed her by the neck and smacked her a few times.. now it's obviously over between us and I just feel sooo guilty.. was it my fault or did she provoke? I never thought I'd hit a woman EVER!