If I were in that situation I would buy a shitty flat, pay it off, then spend as little time there as possible while traveling the world. Maybe have some passive income from the flat by renting it out. Not having kids to worry about would make all that a lot simpler.
But you should do what makes you happy. Try not to worry too much about the future and enjoy what you have now.
It does sound like you may be suffering from depression, but it also sounds like you are receiving treatment. Assuming this isn't something medical, maybe you need a change of scenery to change your outlook.
You could travel, as I would have. You could also engage in a hobby (perhaps with friends, new or old). If you're feeling altruistic, maybe think of something that you wish someone had done for you, when you were in a worse situation. Maybe you know someone who's down on their luck and you can help them. It doesn't have to be with money, it can be in other ways. I've heard that one way to break out of the depression spiral is to focus your attention outward instead of inward. That would be a way to do it.
I hope you find your way out of the funk. As bleak as things look, there are still things to be happy about and be grateful for. Don't let your past prevent you from appreciating the present.