Hi - sorry that this is happening. Why doesn't your h deal with his depression by therapy and ADs, now you both know it exists, and is potentially so destructive.
One thing I have realised if I ever have another close r with a man [either my h or someone else] is that I would encourage emotional self awareness. My h was a fabulous man, now lost in MLC land, but had the emotional self awareness of a newt. I now realise that I need someone who knows what they are feeling and why, who is prepared to admit they are depressed, and could use professional help . . . .