It is really hard to set a new course for life when burdened with so many regrets, failings, long history of low mood. I struggle with it too after all these years, maybe not as bad as yours (my mother wasn't a complete selfish twit) but bad, lonely, alienated, all that. I don't think therapy really helps, per se. I think we help ourselves, and therapy can help that. But we have to be committed to helping ourselves. It's hard to get there when you feel hopeless and don't care. I remember that feeling well. Sorry you are there.