My Ex-went to Vegas with a girl I don’t like

So, my ex wanted us to be friends after we broke up which I was totally cool with. Few months later he became citizen, got his passport and told me he’ll be traveling. I was totally cool with that cuz I thought he’ll be traveling with some of his guys friends. But when he told me it was with the girl I don’t like; my heart skipped a beat and I got so angry. He told me that she bought the tickets as a congratulation present for him becoming a citizen but I called BS on that. I asked him if he was actually going to go and he said yes. So I said if he goes we can longer stay friends. But he still went. I felt so hurt and betrayed. Back when we were dating I was always telling him that I don’t like her and she did not see him as a friend but wanted him for herself but every time I bring it up he’ll cut me off and say I’m over reacting. And we always talked about traveling, we talked about leaving the country together. Throughout our relationships I notice he rather travel with her than with me. I remember one time he asked me if he could go to Jasper (in Canada) with this girl. I was like are you crazy why would you wanna do that?? Right?? Anyways back to the story!! So, he went to Vegas with this girl for a week share the same room which had separate beds; he even send me pictures to show me the beds. I guess he was trying to prove nothing was gonna happen since they were sharing separate beds. I still call BS on it. I was so hurt. I felt like he value her more than more than me. I spend that week balling my eyes out and trying to be ok while he was having fun with her in Vegas. After he got back he had the nerves to tell me that he wants to be friends with and that we should travel together. I told him no I can’t be your second choice. Did y’all think I over reacted or I was right for reacting the way I did. I cut all communications with him but he calls me once in a while trying see how I’m doing. It’s been 5 months now and I am still hurting.. btw there is a lot to this story this is just a preview..