MB, I wouldn't say I have advice, but I'll share my thoughts.
This idea that IC could help turn H around and that the window on R is closing is all in your head.
Maybe it could turn things around. Maybe things don't turn around without that. But I don't have a crystal ball and neither do you.
I feel that trying to get him into IC is controlling and pursuing both. H doesn't need your rescuing, he's a big boy. You can't pull him back, I think that drives him away further. Your best bet is to be the best choice, the choice that is confident, detached, ok with your life with or without him, and not crazy like OW...not clingy, controlling, and worse than OW.
I can see why you feel this situation is an exception to all the DB rules, but I don't think it warrants an exception. Detach. 180. GAL. Keep breathing and focusing on YOU.
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