My ex husband is now in a relationship. He has been seeing this person for 2 months. We finalized our divorce 2 months ago. He told me that while we were separated (Nov 2013) he has been dating. Like multiple people. I don't know what to think.

We ended on the weirdest way. I got diagnosed with Bipolar 2 last Nov. That same week he told me that he wanted out. That he hadnt been happy for over a year, since i had had a pretty bad suicidal point. Up until that time i had never told anyone that i was suicidal. I didnt want people to know. We had been together since we were 17, we are now 34. We grew up together. If there was anyone I thought i could finally tell that I was being plagued by this internal thought that was tearing me apart. He told me that it hurt him so much that for a year he had figured out that he wasnt in love with me anymore. I could tell something was wrong. But he lied. He never said anything until i finally demanded to know what was going on. He said some cruel things that I dont know if ill ever be able to forget. I was hospitalized that week. I was in there for about 5 days. We had a terrible couples counseling session. He would answer my phone calls the next day. We have two children. He decided to leave and take my kids to his parents house almost 4 hrs away. He left me alone in a mental hospital and moved my kids when i had no way to stop him.
In the divorce he held the diagnosis over my head and said that any judge would never give any kind of custody and that if i tried to fight him having the primary caretaker in a joint custody, he would bring up the hospitalization and the diagnosis. So i agreed. I actually thought maybe he was right. It was for the better. He could provide a very stable home, where at that time I thought i could never stabilize. That the kids needed a permanently stable home. Lucky i was able to move to the same city as the kids, and i live with my relative. Im so great full for her support. He divorced me and took my health insurance with him. He knows I need meds. That i need drs help. Didnt matter. The weird thing is that we actually were getting along really well. We had been best friends. We grew up together.
Hes dating someone. He started two months ago. His family knew. I go over and see the kids almost everyday. As i have gotten better i am so much more involved. I feel like the mom i was before everything went black. Im proud of myself. In spite of all that, I picked myself up and registered back in college. It was such a hard process because of financial aid. But i didn't give up. I kept going. Im completing my bachelors in Biology with two minors, Chem and History. Im going to graduate next semester. I have figured out how to continue getting assistance for psych visits and counseling through school, I have gone through the pain of getting prescription help through the drug companies. I just got up and kept going. I stopped drinking alcohol and have lost 60 lbs. Not intentionally but its always a nice perk of meds.
He told me last week that him leaving me was the best thing that could have happened to me, the best thing he could have done for me.
He told me that the kids are going to be going back and forth between our hometown and our new location. He works 24 hrs and he said that his new girlfriend would be taking care of them while he was at work. He said that if i was uncomfortable with that I could drive up there and visit while she was watching the kids, that he was trying to compromise. He said that I dont get to decide where he takes the kids or who he has care for them. He says that anything i worry about is me being paranoid. That im the one out of line. Im the one hurting other people.
The idea of him dating didnt hurt at first. I knew he would. I am surprised that it was really soon after the separation. I am still trying to be good friends with him because we are going to be in each others lives forever. There is no other way to be. I don't love him. I probably stopped during that yr of being ignored.
But now I am so angry with him. Im so angry. Im so mad and all I can think about is that I want to feel something else. To not feel any emotion for him at all. I want to feel anything else that can make me forget. I know with just a bit of time and perspective I will be able to keep going...but what do i do till then. I know this sounds so wrong to even think about, but why was i so easy to leave. Why was it so easy.
Sorry this was so long. Thank you if you got all the way to the end.