I once had an affair with a married man while I was seriously involved with someone else. Please don't take offense to my comments as I am really only reflecting on my prior situation that occurred many many years ago. But, I did it because I was unhappy, not just with my BF at the time, but with my entire life. I was seeking escape & fell into the arms of the first person who made me feel good about myself & gave me some attention. I think he did it for a lot of the same reasons & at one point told me he was going to leave his wife for me. I truly regret the entire thing & have vowed I would never cheat on someone or get involved with someone who is cheating again.
While we both cared a lot for each other, in retrospect we didn't love each other, even though it felt that way at the time. We both were miserable with our own lives & using each other as an escape.
My guess is that if this man cares for you drunk, then he will care for you sober. However, he likely has a lot of emotional issues, which are probably part of the reason he drinks. You are likely his escape from his own unhappiness - like drinking you are another temporary fix for his internal pain. I would not expect him, drunk or sober, to leave his family for you. I also would not expect that you would find that you would really find long term happiness with each other. Leaving his wife & being with you would not actually fix what is wrong with this man. Also, you likely have some emotional issues as well or you would not find yourself needing someone who is unavailable & your issues wouldn't be fixed by you two getting together either.
Just my 2 cents from my past experience. Get some counseling & move on with your life.