I'm often the first person to suggest couple's counseling, but my first impression when reading your post was that making that kind of investment in this relationship would not be good for you in the long run. It sounds as if you already know there's big trouble here and know it would be best for you to leave.

In my own mind, I switched the genders and asked what people would say and what I'd say if you were the female writing that her boyfriend flew into a rage and had started slapping the hell out of her during sex. What would people say?

Run. And don't look back. It would be unanimous. Men don't deserve to be slapped around any more than women do. Especially during sex, when you're in an intimate and vulnerable state. If she can go into a rage, with the urge to draw blood, because she doesn't like a basic aspect of your personality, how could you ever relax or trust her? If it was erotic and you were both into it, it would be great. But his is something different.

Run.