My ex-partner’s thoughts about me feel very persuasive!

My partner and I separated three years ago, when our son was 3. At the time my thoughts about him were that he was unbearable, a narcissist and an over bearing bully. His thoughts about me were they I was a complete failure a liar and that I always let him down. Happy days!
After leaving him I spent some time complaining about his behavior but I never liked doing this and always knew I needed to clean up my side of the street!
I tried various self help methods to get me into a position of accepting responsibility for my feelings about him but would still find myself furious or upset when he would suggest I was failure or that I had wronged him and I tended to opt for silence and make a hasty exit if it looked like we were veering toward that kind of conversation.
Last year we decided that we could, for our son, find a way of living together but not being in a ‘romantic’ partnership and we took the decision to buy some property with our extended family. It sounds like the good life and I really believe it can and will be but still I find myself in arguments and heated discussions with me hearing him say the words that I have failed him, let him down, that this let down is tantamount to abuse and when he lists all the reasons how and why I end up finding his views quite compelling!
I’m left this evening, after another of these stream of consciousness rants thinking what reparations can I make rather than thinking that I don’t need to believe this thoughts about me and this keeps happening.
C – Conversations with my ex-partner
T – He is right I have let him down (perhaps I am abusive)