Need your help r/gay, break up advise.

Shortish term lurked, first account made today.So here's where I'm at right now. I'm in a relationship with the best guy I've met, he treats me well, respects what I ask of him and lets me do my own thing...when he's not drinking.About a year into our relationship he got really into drinking. REALLY into it. He'd go on benders for a few days. These benders would always include fights and threats to break up, coming from the both of us. About a month ago, I came home from work and he was passed out with Grindr open on his phone. Tons of conversations asking people to hook up with him before I got home. I confronted him about it when he woke up and didn't remember a thing. I left him. But being the idiot I am, I eventually came back. I've told him countless times that it's either alcohol or me (even though it's selfish, but I can't stomach seeing him drunk after the Grindr incident), and he always chooses another drink. We always end up saying it's over, but I never get the thought out of my head that I had the best times with him when he's sober. Hell, I would've said yes when he proposed if he never started drinking. I've tried to get him help but he never accepts. At this point is it just a lost cause? Just kind of at a loss if I'll ever get the man I loved back again.