Why can't we both let go........

My stbx and me talk often.  We don't talk about us, we talk about the kids, about work, things in general.  I'm still moving forward, taking care of me, I don't cry or beg him, I dont do anything for him, except talk to him.  I can see a little bit of my future and I'm not going to lie, sometimes I still wish he was part of it, but I don't wallow on that idea, I keep moving forward.  I've told him to live his life and I'm going to live mine but then I wonder why can't he just let me go, yes he did leave me, he was involved in an EA with OW, he fell in love with OW, he emotionally divorced me a long time ago so why can't he just let go, it was his decision, his choice, he wanted to leave, he dont want to be married anymore so why does he keeps calling me, I dont email him, I don't call him, is always him initiating contact.  I'm so weak that I always answer, I'm so weak that I can't imagined myself telling him to just not call me anymore, I think it would be so much easier if he just didn't call me at all,  if he was just an asshole.  It's bad is he calls it's bad if he don't call since I still look forward to talk to him, if he was an asshole instead of nice to me when we talk it would be easier for me to say "Fuc....it!!! I can do no contact and just cut him completely out of my life but I can't cause I still love and miss him, but he don't have any excuse, sometimes I think he is just bored, I'm just a distraction until he meets somebody else that would ocuppy his time.  Some days I just want to tell him to leave me alone so I can really move on and some other days I dread the day that he does stop talking to me cause he has somebody else.  Argghhhhhhh bad both ways.  My feelings are a contradiction - I want to move on but at the same time I can't stop talking to him.  I don't cry him as much as I used to, even the sad memories don't trigger me as much, I'm not angry anymore - Yes I still cry and get angry sometimes but is not consuming my insides.  Why it is so difficult for the both of us to let go.