That's a tough one, when my alcoholic partner was still drinking it was annoying having to babysit him when he would over drink. You can practice the method of detaching and not enabling him when he goes overboard or you can just remove yourself from the room when he starts drinking. When asks why you don't stay in the room, tell him that it bothers you and you want to remain sober.
Luckily my alcoholic partner also stopped drinking, so I don't have to worry about it. Who knows, maybe yours will too.