Ex Fiancé Problems

I need advice but want this to be anonymous. I have been out of my last relationship for about 5 months now. We were together for 5 years. But we have still been seeing each other and sleeping together. He is currently in another relationship. I can’t have children but he wants one of his own which I understand. But I don’t think it’s fair to her or me with him just using her for a child and then wanting to come back after he gets one. I don’t believe I could cope with that or having to see her on drop off and pick ups. He is breaking my heart like no bodies business. How do I get past him and move on, besides the stopping all communication? That is the easy part. I’m talking how do I heal from everything? I don’t think it’s fair how he left me because I can’t give him a child. And after so many years together, I am lost.