Does your therapist have any ideas?

I would be inclined to redefine it as a problem of excessive guilt or shame. Then I would use mindfulness, CBT, or DBT skills to deal with these emotions.

My son has issues with blaming too. I think he blames himself for negative things, then he feels so bad about himself that he pushes the blame onto someone else.

We'll be having argument. He'll give his side. I'll give mine. Then he'll say, "So it's all my fault?" I've asked him to drop the idea of blame. If we have an argument, it's likely that we share the blame. But it's so much more complex than that. Maybe the guy who cut me off in traffic earlier that day is a little to blame too. Maybe the person who was rude to my son at the store that day is a little to blame. It would be impossible to totally tease out who all is to blame and to what degree. We'd have to know everything about everyone all the way back to the beginning of time to decide who's to blame. Maybe if we could know all that, we'd just decide to be kind with ourselves and everyone else and relax in the knowledge that we're all doing the best we can under the circumstances.