As they say here it sounds like your depression is talking. They also say that depression lies but I am not sure of that. Sometimes I think depression delivers brutal truth. It sounds like you could also use some DBT style acceptance therapy. That is...accept how things are...while being willing to change.

I personally don't feel that anyone is doomed. Look, for instance, at Stephen Hawking. He was given a death sentence in his early twenties. He went on to marry, have children, write a best selling book, inspire a movie about his life, have a long standing career, and produce TV shows. And he hasn't even had a real voice since he was young...only a computer voice.

I do exactly as you do. I am almost always in the past digging up dirt. But I am trying to stay more in the present. Mindfulness exercises and techniques, and having goals is helping me stay in the present. I am choosing solution based thinking over digging around in the the past...although I still keep going back there and have to continually haul myself into the present.