I've hit (well not really hit) 2 women in my life and both were well warned and know full well what my temper is like.
1. a GF and I were arguing and she had the BALLS to get in my face and stick her finger in my face..and after many warnings telling her to back up she accidentily poked me in the face.
I lost it grabbed her by the throat, picked her up and threw her up against the wall. she never did that again and I never layed another hand on her.
2. a friends on mine had a GF that thought it was funny to pinch people(which i fuckin hate to be pinched) and I mean pinch so hard that she bruised and broke the skin.
Everybody would get pissed when she would do it but she kept on doing it. I told her one day not to ever do it to me or I would smack the shit outta her.
He response was "you cant hit me I'm a girl", so she preceeded to pinch me and I slapped(open handed) her in the mouth so hard that she did kinda a half backflip/cartwheel.
she stopped pinching people after that.
Bottem line is that there are people out there that will fuck you up if you cross the line with them.