He is using the kids and the threat of divorce and 50/50 custody as leverage to try and get you to "go back" to the way things used to be. He is even "recruiting" others to tell you to let him drink in his own home. Don't fall for it, just tell him that if he does not give you physical custody that you WILL ask for a court ordered eval. Drunks hate scrutiny and will do anything to avoid it.