One of the most helpful views I ever read about envy was from Aristotle. His view was that it was a wish to emulate someone, but that the person also believed it was impossible for them to do that. And that sounds like what you've described.

A wish to emulate someone, to copy something they have done well, is really a helpful thing in life -- we don't have to figure everything out new for ourselves. We can see what someone else has done that we would like and, if it is possible, we can make arrangements to try to do the same, or similar, for ourselves.

In this case, though, your wish to work toward having your own flat like that seems stymied. You said that you felt low and hopeless about making such a path for yourself.

I don't know how you do it, and apparently your therapists haven't known how to help you do it, but I wish you that you could find a way to look at your positive characteristics and get excited about using them to get what you want. I know that you've been having problems and are currently unemployed but you're well educated and write well in English, not your native language. And you may have more positive characteristics and talents that you haven't written about here. So those are really something!