Is it the deep-seated, irrational fear that he was right about all this and the reasons he gave for leaving, that I am a terrible person...so, I am trying to prove it was all his fault? The flip-side to his constant blame-game (so much easier to see in others than in yourself).
I think the very fact that you can be circumspect and question yourself about that is a strong indicator that you're just fine. You're just a normal fallible human being just like everyone else, except that you have the insight to try to check and manage yourself. If you didn't have these questions, then you'd have something to worry about. KWIM?
But try to not let these same self-doubts continue to drag you down -- we have to keep those in balance as well. (Easier said than done, I know.)