You don't need me to tell you that trying to argue with a drunkie is like teaching a cat to knit.
But your question--why am I trying?--is really at the heart of the dilemma.
You're trying because that's what decent people do--they try to stick through things with their spouses. Don't beat yourself up about it! I'm guessing you weren't a trained addictions specialist when you married him, right? So how were you to know that alcohol addiction is a weird sort of allergy that eats up a person's mind? Of course your first thought is to talk sense into him and help things get back to normal.
Unfortunately alcoholism is unique in that there's just no talking to him. He'll quack and quack because all that's going on in his little brain right now is ALCOHOLALCOHOLALCOHOL.
RE: leaving. Your son deserves to be away from this crap.
RE: driving on suspended license. If your husband injures or kills someone whilst driving on a suspended license--whether he's drunk or sober--you could be sued in civil court if it came out that you knew and did nothing about it.