My wife left me after watching me slowly try to kill myself and learning of my infidelity. I wanted to love her but I did a terrible job of it. Unfortunately I had never learned how to love myself so I was incapable of loving even a pet goldfish, let alone a woman.
My advice to you is to put your needs and your emotional wellbeing first. It is not your job to fix him and trying would be pointless anyway. Only the alcoholic can fix himself/herself.
Towards the end of my marriage my wife asked me why I wouldn't stop drinking for her. It's because we're broken people spiritually. Until we resolve to get better alcohol will always take precedence over love, family, career, goals, all that good stuff. I wish I had a better explanation for you but I don't.
I wish you the best of luck.