Devasted. He cheated on me with his ex.

This is going to be long. Looking for support, how can I move on from this?

Hadn’t dated in a long time. Met in early August, agreed to be in an exclusive monogamous relationship in October. We spent Christmas Eve, Christmas, and New Years Eve together. He (57m) met my (52f) family. I met his adult daughters. Then a few days later, he sabotaged us with his ex-girlfriend (55f).

I wasn’t in love with him, but I think I could have gotten there. On New Year’s Eve, I asked him to make love to me and be sweet, and he did, smiling. Things were going good. We were highly compatible, had a lot in common, we could have deep conversations, the sex was good. The only major issue was that he wanted to continue to see an ex-girlfriend as friends, just the two of them. Didn’t want me to meet her because they “never hung out in groups.” He mentioned me and she changed the subject, didn’t want to hear about it.

This wasn’t his ex-wife of 20+ years. It was his first significant relationship since his divorce. They were together for 8 months, had constant problems, she wanted to be non monogamous and he didn’t. He said that he didn’t want to get back with her, they couldn’t have emotional conversations like us, she didn’t know him as well I had gotten to. I was very uncomfortable with it, particularly when he told me that he’d bought tickets to see the same band on two nights, Friday with her and Saturday with me. That made no sense to me and he couldn’t adequately explain his thinking there.

We almost broke up over her multiple times. He said that his ex-wife had conditioned him to think that he was going to mess up and hurt people and he was going to hurt my feelings because he would. He also said that he had lost himself in his marriage and he didn’t want to give up this friendship. I felt like she was in our relationship, setting boundaries and I was powerless. My choices were to let it go or to leave him. I’m in therapy and talked about this with my therapist. We decided that I’d only been in his life for a few months, everything else was going well, and I’d see what develops with this.

I hadn’t heard about her for a few weeks and was disappointed when he mentioned he’d made dinner plans with her for a Saturday. I had a really bad feeling about it and we had a long conversation. He agreed that he would tell her about me and say that I wanted to meet her. I wanted to observe them together. I was upset and crying that day and told him I was feeling very fragile. He reassured me that their friendship wasn’t a threat.

The next morning, he sent me a text that I was right and he’d done the worst thing that he could do. I called him twice to get more information, but never saw him in person again and got to look him in the eye. He says they were drinking back at his place, he mentioned us and that we were good together and that I wanted to meet her. He also told her that she was the only issue we’d had. I think the fact that he had something good and someone else wanted him made him desirable to her. They started making out and tried to have sex but his ED wouldn’t let them. I don’t think it was premeditated because he didn’t take his pill apparently.

I can’t understand why he would do this to me. Up until a couple hours before their dinner, he was telling me that she wasn’t a threat to us. A few days earlier, we’d met each other’s families. He says he self sabotaged. I offered to forgive him, but he said he would never forgive himself and couldn’t get past hurting me.

Someone that would hurt me like this is obviously not the guy for me. But we became so close, took things slow, and built a friendship before our romantic relationship. I can’t make sense of it. His two longest, best friendships are with women, not exes though. I had no issues with them. He also has two adult daughters. The fact that he has so many women in his life was a good sign. I could tell that he prioritized the relationship with this ex over us and something seemed off. I should have broken up with him the first time that we disagreed about her, when he canceled plans with me to spend a Saturday with her. This was a few days after we’d gone out of town together and were in our honeymoon phase. I was so hurt by that.

I’m trying to move on and also figure out what lessons to take from this whole experience. And meanwhile, I’m so sad. I’ve lost a bunch of weight and I just can’t shake it off.

ETA: thank you to all who gave me support and suggestions. He was messed up and broken and you all have validated that. I’m closer to moving on and starting to be able to eat again, although lost 15 lbs in the last 3 wks. Peace and kindness to anyone reading this far❤️