Hi zircon, I know the feeling. it always comes back to us needing to change our expectations and understanding, seems so unfair and out of whack but I have found as the haze clears and the sadness settles in acceptance will follow. The situation is what it is. I have been reading so much on here about codependency and letting the A in your life fall and find their own rock bottom.
I had the same misgivings as you, where will he go? How will he live? Even this morning I had a real fear that he would commit suicide, (no proof just no contact). Later on in the day I had a message, sigh of relief, over the top sense of all being okay.....but I realised the mind games and my addiction to looking out for him and rescuing him hijacks my mind just as his addiction to drinking overtakes him.
I wish you peace and hope you find the path that leads you to happiness.