Personally, I've found it a difficult decision to make, stay or go? I've left my AH only to come back again. At one point I found myself in pretty much the exact position you are right now, promising to change because he didn't want to lose his family over something as stupid as alcohol. I've always bought it hook, line and sinker and ran blindly back to him.
Unfortunately my story doesn't have a happy outcome because he still drinks. He's not a daily, slobbering drunk, but rather a slightly intoxicated 3-4x's a week guy that spits out mean, hateful thinks that I'd never say.
Our senses get mixed up because we are tossed bits of the person we all fell for in the midst of some drinking and verbal assaults. Most of the time I think logically we can all perceive what needs to be...leave and let the other party deal with their problems. Emotionally, it's very hard detatching from the person you once knew and still very much love despite all things.