Darls, as you say, you are not ready to be his friend, you really aren't. Of course you aren't. In my sitch, I am not either, but I keep 'doing myself in' by trying to be something I am not (e.g. maybe a friend, when I want to be treated like his W, or be calm when actually I am angry) and each time I am about to meet up or have a conversation with WH I think to myself, THIS time I'll keep my calm and not lose it, and fail almost every time..!! As long as I judge him and have no respect for him, nor feel respect and remorse from him for leaving me pregnant, I can't "be friends". It took my parents over 2 decades to become "friends" after their amicable-enough divorce.
Too much contact, where we start to talk "issues" actually destroys (I think in my sitch has already or alrady destroyed) any chance of me and my H of being friends. I've now told WH that I don't love HIM anymore. You see...it can just degrade further and further (probably because of my personality - this may not happen to you - I'm too reactive a person to maintain a constant High Rd for more than 20-30mins!!).