Been there - sorta. The only time I ever hit my wife was when she had me in a choke hold and I was on the verge of blacking out. One quick shot with a closed fist to just below her left eye was enough to make he break the hold so I could run from the room. You actions were not unreasonable, but yes you are a wife beater (as am I - deal with it) and no, you should not have shot or otherwise escalated it. This isn't the type of thing you can't come back from, either - mine was the low point in our relationship, and things have been getting better ever since - we both just needed that one crazy moment to let off some steam...