I learned in Cognitive Behavior Therapy that "all or nothing" thinking made me either depressed or angry - like either it is all my fault or someone else is to blame etc. I learned to strive for rational thinking - rational assessments of my situation.
I accept 50% of the "fault" for the end of my marriage. But only 50%. No more- no less. When I got out of the marriage I focused on ways I could change, because I really didn't like who I had let myself become. Accepting my fair share (but only my fair share) was a huge relief- I didn't have to beat myself up anymore - I just had to decide what changes do I want to see - in ME?
Good luck- I'm glad you're posting lots - you're bringing up timeless issues and interesting stuff!
peace-
B.