You seem like a very aware, intelligent and sensitive guy who really loves this woman. Unfortunately, you also (by your own admission) have a violent temper and have hit the woman you love so much. My suggestion would be to get yourself into some type of anger management counseling — one geared towards dealing with domestic violence. Once you’ve taken this step, perhaps you could ask her to attend some of the sessions with you.
I think you need to seek help for yourself as well as for anyone else you may become involved with. If you don’t, you will end up hurting someone with you going to prison.