He's taken no steps (IC, lots of exercise, or psychiatrist visit and meds) since, right? According to my IC, depressions can just "lift" like they came, but it can take an awfully long time and sometimes they don't.
Hang out with him this week and ask hiim to take the focus off you for a month and please put it on himself and what he can do that doesn't involve you or your R to make himself happy every day. Try to reframe it maybe? Without suggesting meds and all that?
He might D you thinking it will rid him of his obsessive thoughts, but it won't if it's depression. He'll still have the obsessing.
What a mess. Sorry tonight went this way. On with the rollercoaster.
How long do you think you can tolerate this? Twelve months?