TLDR: Me (F27) and my boyfriend met while we were both seeing other people and we slept together. I asked him where the things with this girl he was seeing were going to which he said “things with her were not going anywhere”, however, after we got involved he when to see her and they slept together.
He says he intended to go see her to tell her about me and end things between them, that he did not want to sleep with her but he got extremely drunk and she made the first move. But that he regretted it immensely and after that he told her about me. He says that even though we had been involved he was extremely insecure and he did not know how things were going to go with me, that he thought I would be seeing other people and would not want a relationship with him.
How do I move on past this?
We have been together for four years now but I can’t forget this. To add to that, recently I asked my BF to see his messages with her and I am shocked. He at one point told her “would be great to speak again, I do miss your voice”. And he has also sent her a really expensive (100€) book with a letter.
On top of that, she messaged him saying she misses him and that he his the only man who knows her heart completely and he replied that she knows his heart too, she understands him and very few people do and that he knew they had a strange special connection since they met.
I am now absolutely traumatised and believe he simply used me, and had feeling for this person during our relationship. That maybe he went to see her after being with me because he was unsure of me and still wanted her.