You think it because he is...
One thing that is certain is that he is an alcoholic. Don't question yourself on this. And, by the way, he's not qualified to have an opinion on this because he's an alcoholic.
Another certain thing is that you did not cause this, you can't cure it, and you can't control it (but you can contribute to it).
When I was lost about how to handle my wife's drinking I eventually found Alanon. It's the best choice I've ever made.
It didn't stop my wife from drinking-- she continued to drink for several years. However, it did allow me to interact with her in a safer and better way.
Good luck Mimic, and take care.
Cyranoak