Did he HIT you, or did he just give you a good slap? In all honesty, I think there is a big difference. I mean, it's pretty acceptable for a woman to give a man a good slapping. Why not the other way around?
I have to say, I slapped Kathryn. Twice. She was shocked as all hell, but we agree it wasn't abuse. My reason for slapping her was totally unjustified and wrong (in hindsight), but I think that it is important to express your anger with your significant other, preferably in a healthier manner.
Really though, what is the difference between some yelling (verbal abuse) and a slapping (physical abuse)? Personally, I'd rather get a firm slapping than be destroyed with words. So, not that I know ANYTHING, but try to put some perspective on the situation and then ask yourself how 'abusive' it really was.
So, say, if you had cheated on him, and he slapped you, I would consider that justified. So, why did he slap you exactly?
All that said, it's probably best to get some space and time between you. Even though this whole thing w/ Kathryn has been tearing me to shreds, I feel far more whole and at ease with myself since we've been apart.
So, I say separate, go to your own corners, figure things out with yourselves, and then revisit the situation later.