Your situation is heavy as you said. My H is also has substance abuse issue. One of the reasons he uses is because of his depression that he won't admit to.

I don't have any advice to give as I am a mess but want to send you some encouragement.

Me 44; H 48
no kids together; H has D24, D19
M 14; T 18
DB 12/21/14
living together (for now)