how can I be with him when he thinks so badly of me, and how he KNOWS I have left him for someone else because he apparently knows me inside out and if I loved him I wouldn't leave him. Told him a million times there is no1 else.
This is insecurity in him. Needing to constantly have someone prove their love. If you love yourself you don't have this constant need. This is the opposite, self loathing.
We buy into the manipulation because of our insecurity, our self doubt. Did I do something wrong? How can I fix this?
Don't buy in klacey. From what you write you were capable of reciprocity which is important in a healthy relationship. Shifting our focus to our insecurities, grieving our loss and building our emotional maturity is key to future relationships. Whether it be romantic or otherwise.
Hang in there.