Dealing with depression partner

I am a 29yo gay dude in a 10-year relationship with an amazing guy that is struggling with long time depression. I am not dealing well at all with the situation: we can only have sex with other people and I am really missing the romantic side of the relationship. He's still a student, having difficulty in graduating hence getting a job: we cannot live together as he can't pay rent and we rarely travel or enjoying festivals and parties as he's depressed and with body-issue (although I really much like his body). I already know we should break-up but I am so afraid he can get more depressed and will never graduate also because of me. What's more ethical? Stay and try to help him out while seeking romance with my sex partners or being honest and tell him I simply can't stand this frozen relationship status?

I don't have advice for the whole situation but if you wanted to stay together for him and not just the depression: you could see if he'd be open to talking with someone in therapy. Otherwise just keep being there for him, don't give up on interactions, and maybe see if inviting friends to see him helps (if you're not all up in a covid lockdown).
I know this is kind of generic but I dun wanna assume too much more.
Oh and think about couples counselling if that's available.