HaWho, Your h is taking very small baby steps He's helping the kids w/their homework and he inquired as to if you were feeling better. These are steps in the right direction. You have to look at the whole picture and I can see some improvement in his behavior once in a while. Far, far different from a year ago.
He knows that he's in a safe environment and you've not put pressure on him to straighten up. He's comfortable in his dorm room and the only way that I see him moving out is if you put a lot of pressure on him or start getting on him, i.e., like a mother would do. You've keep your home relatively calm, quiet and safe. Unless that changes...he's there for the long haul.
All you can do is guide your boys and show them the unconditional love and compassion you have for them and their father. They are very much aware that something is off w/their father and hopefully this will not be something that they will be harmed by because you've been the strong, lighthouse for them as well.
Keep up the good work. Maybe the Easter Bunny will bring him an Easter Egg that will bring him good tidings and help him get himself together and return to the land of the living.
Sit quietly, the answers will reveal themselves when you least expect them to. The past is gone, the present is a gift and you need to focus on today, allow the future to reveal itself when it is ready.