My situation is similar to yours, only the pieces fit together a bit differently. In this case I was the unhappy, functioning alcoholic husband stepping out on my marriage. Neither of us was/is happy, and we hadn’t been satisfying each other intimately (sexually and otherwise) for a long time. I met another woman over the summer, and we fell madly in love. The new woman recognized my alcoholism pretty quickly, though, and told me she wouldn’t see me until I completed a year in AA, working the steps. I’m still in that year, but I’m a much happier, much less selfish person. My marriage is still going to end (we’re separated now), but both my wife and I are much happier as a result of my work on myself.
I tell you all of that to say that getting into AA, practicing mindfulness and getting outside of myself finally helped me find true happiness. It sounds like your husband is pretty selfish, and I only say this because he sounds a lot like me. Booze makes the brain selfish, so it seems it’s impacting your relationship with him in a couple of ways. I’m not saying that you need to give him an ultimatum, but getting into a 12 step program might help your husband. It might help you see some progress in him, too, and give you reason to stick with it. Like Anita suggests, separating” while staying in the same house could help (it worked for me).