My ex monkey branched and gaslit me and idk how to move on

Please give me advice or tell me what mindset I should have to move forward

My ex monkey-branched with a guy that she had a situationship with a few months before we started dating. When she dumped me, I went into a phase of checking social media accounts and noticed that she re-added him. Throughout the relationship, she said she never had feelings for him and that she chose me over him because she liked who I was more. Now she is actively rebuilding a relationship with him.

The issue I have is that when I reached out to her a few weeks after the breakup to tell her I knew she went back to him, she said she only went back to apologize for how things ended in the past. She framed it as if it was just about closure and apologizing for her actions. But from what I can see, it doesn’t look like it was only an apology, because she is now friends with him on Steam and they are actively playing games together consistently.

Because of that, I feel like I was lied to. I believed her explanation at first, but her actions don’t really match it. At the same time, I keep going back and forth in my head trying to figure out what is true and what isn’t.

For about two months after that initial message, I felt like I was mostly over it and wasn’t really thinking about her anymore. But recently, I started getting really obsessive again about what is going on between them. I ended up checking their profiles again even though I know it doesn’t help me.

I got sick of doing that, and I decided I was going to message her again to tell her that I believe she wasn’t honest in her last messages and that it wasn’t just about apologizing to him. But now I feel ashamed about having sent or wanting to send that message, and I don’t know if she will even reply.

Part of me feels worthless and stupid for still being stuck on this. I also find myself thinking about how he might see me, especially since he now gets to be with her, and I end up feeling like I’ve been replaced.

There’s also another detail that might just be me overthinking. On his Steam profile, he has a new badge that can be gifted using Steam points, and it says “winner.” I know logically it probably means nothing, but I had previously told her in messages that he was “the winner now,” so I can’t help but wonder if there’s some connection. I also recognize that I might be reading too much into small details because of anxiety, but it still sticks in my head. I can't move on knowing they happy im alone