When you did talk to him, did he not string you along and mess with your heart and mind? So what do you think the answer is to your question about NC? NC isn't about punishing (or at least shouldn't be IMO) it's about positives for you, like gathering your own strength and getting some breathing room to deal with your own emotions. I know it's hard. I'm still struggling with it. Everything from if it's the right thing to do, to my own motivations for doing so. That he would not talk to the kids in an attempt to punish you (which is what it sounds like) is pathetic.
Remember that setting boundaries for yourself is not mean. Mean comes from a place to intentionally hurt. Also, aks yourself, is he really being a friend to you? I think on our end (at least at first) we cling to the "friendship" b/c it gives us some contact and we feel more hope. I'm not ready to be friends and I don't know that I ever will be. That doesn't mean I can't be civil and co-parent our D's. I just don't know that I'll ever (personally, with just me) invite him to anything or call just to say "hey" what's up with you?
