Sucks

Ex boyfriend cheated on me. I found out days later when I saw that he was going on dates with her. He’s also added his old exes on social media and shit. Now it looks like it didn’t work so now he’s trying to get with a girl that he’s left me for before. He met this girl at a party and she had just left her ex boyfriend and my ex had just left me too( he left me for a diff girl). They were going on dates and one night he texted me saying it wasn’t working with this girl, talking shit about her, and that she’s not me, that she’s just a distraction and that he wanted to get back with me. Next day he dubs me and I see that he still went out to see her despite everything he had told me that night. I was hurt again and then time goes by and he ends up coming back to me because she decided to get back with her ex. They were just using each other basically, obviously rebounds. Now he’s trying to talk to her again and this all sucks, looks like hes very desperate. I thought he loved me, our relationship was long term and we had planned a whole future together. I see him doing this kind of stuff and it does hurt a lot. To me seems like he’s just trying to forget me by going out with other girls and going back to other girls that he’s left me for Cz it’ll be easier to get with them. Yes hes cheated on me before many times but I thought he would change, surprisingly this time around I didn’t expect it at all. I never thought he’d cheat on me again☹️ & now he’s trying to get with this girl when it’s only been a week of us breaking up. This girl is also aware that my ex had cheated on me before and I also told her that he had texted me that night and I told her everything bad that he had told me about her at the time. So I’m sure she still remembers everything that I told her so now idk if she’d still choose to be with someone like this. Any advice for me on how to move on? It’s hard for me because I’ve only been with him and we were together for so long.