First of all, alcoholism is a mental illness, classified thus by the American Medical Association. And, a huge percent of alcoholics (both recovering and not) also suffer from other mental illnesses like depression.
But this must be about you. There is nothing you can do or say that will affect his drinking and it's good to know that alcoholism is a progressive disease. Is this what you want for yourself in life? Because it isn't going to get any better than this (unless he gets sober for his own reasons). A really great place to learn how to "moderate" relationships is Al-anon, which can be a life saver. I hope you try it.