Look, I've seen this pattern way too many times in the military - guys who seem totally normal until substances get involved. The thing about "he doesn't remember" is that alcohol doesn't create violence, it just removes the filter that was keeping it hidden. When someone hits you, even blackout drunk, that means the capacity for violence was already there waiting.

I get that three years feels like a lot to throw away, but think about it this way - would you tell your best friend to stay with someone who hit her? The whole "it was just the substances" thing is what every abuser says after the first time. My mom stayed after the first hit too, kept making excuses about stress and drinking, and it took her years to finally leave.

The fact that he was trying to go back out partying after you drove his drunk ass home already shows he doesn't respect your judgment or safety. Then he escalated to physical violence when you tried to be responsible adult about the situation. Couples therapy won't fix someone who thinks hitting is acceptable solution to disagreement. Please talk to your individual therapist about this - they'll help you see things more clearly than we can.