The more you try to influence him the further he will have to run to escape your influence. When you take the leash of and let him run away, at some point he'll realize you aren't chasing him or tugging at him.
This doesn't mean he'll come back. But at least he'll have the chance to see where he is, learn the consequences of his choices, and decide what his life wants to look like. I don't disagree that getting IC is a better choice for him, but you don't get to make to make those choices. It's no different than if he became a drug addict. You can't make him quit or force him to hit rock bottom. Some never do. It's not a healthy decision, but it's clear you're the last person on the planet he will listen to, and he will surround himself only with people that minimize his actions and tell him what he wants to hear.
How long will this take? Maybe through the D proceedings, the grieving process, and the rise and fall of his A, along with some soul searching afterwards. It could be a year or two, and he might never return, or it might take so long the door has been shut.
It's brutal. Especially because it's clear he's confused and conflicted. But this is the path he's chosen, so I hope that you can gain some closure and detachment and let him go on his way now. I
Me:38 XW:38 T:11 years M:8 years Kids: S14, D11, D7 BD/Move out day: 6/17/14, D final Dec 15