Faith welcome to the forum. you have a tough case but you have stated the obvious. First, for your sanity try to find a Al-Anon meeting close to your home. Please attend and participate, for your sanity. This next suggestion is hard but fair. Somehow put your 27 year old son out. He is an adult and he should be made to swim or sink without having a pity party. Toughlove is sometimes all our love ones understand when they are caught in the grip of addiction. You take care of you, God will take care of your son.
God Bless and be strong.
Just for Today-------I am Sober