Dear Colonel,
I joke a lot about Lutheran guilt being worse than Catholic guilt, but oddly on a deep-seeded(sp?) level, I think it is true. I take it, and forgive me if I'm wrong, since you are German you are probably Lutheran and the thing here is we are told to suppress our emotions from a very young age. We are to stay stoic and be responsible... etc. This leads to us not truly finding out who we are. You say that you're depressed that your parents might be breaking up but I don't think it is or ever has been your fault that your parents are breaking up. Yes, it is unfortunate, however you are 22 years old and I doubt this will affect your life as much as it would if you were, say, 2 years old or 12 years old.
I think you may be clinically depressed. In that case, your next step would be to go see a physician. You cannot rely on self improvement strategies, per se, if you're ill. However, it could be considered a self improvement strategy to get your butt over to a doctor!
I think you've come to the right place. What I found helped me out of my rut, was helping other people. Even sharing on this board helps. Is there a question that someone is asking here that you think you could answer or where you could, at the very least, offer a similar experience?
I hope things get better for you. I know right now you feel a dark cloud over you, but it does lift. I know, I've been through it also. I wish you the best. E