Has he been to therapy? If not, is he willing to go? Sometimes when extremely depressed it's hard to want to help ourselves, so taking the initiative to go to therapy might be difficult for him. I struggle with this a lot myself. We see a lot of "why bother, there's no point" when it comes to trying.

It's so refreshing to see parents that care about their kid like you do. Myself and others here have not been so lucky. Thank you for being a good parent.