I have treatment resistant depression too and have finally given up the unequal and retired on health grounds. (At 45)
My husband thinks I should have done it earlier.

I really feel for that sense of guilt, I feel it too and have to challenge it all the time.

Now I'm not working, however, I have more energy for my friends and husband and have been able to support a friend in a way I couldn't have if I was working and they say it helps them get through. I am also free to do two hours a week volunteering which means I can do something useful to contribute to society without the responsibility and pressure that would make me more unwell.

I'm only saying this to try to show that worthwhile life doesn't have to end because you need to be on disability.

Best of luck as you try to find a way forward.