Yeah it's a loaded topic and it's tricky. People who say that one day, the definition of a "German" or a "European" will change are deceiving themselves. Even the whole topic of colonial and wartime guilt that forms the basis of this country's modern identity really has nothing to do with "people of migration background". I mean, every time you hear someone say "We as Germans have a moral responsibility to atone for the past", they're not talking about the passport Germans, mkay? Just accept it for what it is and don't try to think about it too much. If it really is affecting your mental health this much, I'd say make plans to leave but don't do anything rash.