How did you get okay with the fact your partner is now with someone else + a different person who you once dated? Reality is so confusing for me right now.

Sorry for the long read!

Context : I got cheated on by my long term gf during her masters. I tried to reconcile but she chose the guy. The guy is a total downgrade imo as well my and her friends as well. She proceeded to block me everywhere because she needed to “heal” and after promising to not date him she started dating him and moved in with him. She after 5 months cheated on that guy with someone else and is now dating the new guy. She has lost her friends on campus as well as the common friends as well because after cheating on me majority chose my side except her best friend who is still very good friends with me and openly has accepted how bullshit of a person she has become. On campus because she cheated on the guy as well in her same friend group they all chose the guy and has no one right now except the new guy.

The reason am claiming she is such a different person is due the below actions :

1. She was once such a emotional person suddenly post cheating on me become cold as fuck like didn't give 2 shits how I handled it or how I was even doing just blocked.

2. She overly started posting on Instagram about the first guy (my friends told me cause I was blocked) and how they were having fun but couldn't care less because I knew this was not going to last plus he looked nothing like me a total total downgrade. But this was the woman who never posted that much about me, I didn't either as well we always kept it lowkey on social media.

3. The person who never used to lie started lying so much to everyone around. First to me on the cheating nonsense then when she cheated on the guy she cheated on me with she started telling everyone that he was so insecure nothing like me and I do not want to date and all but was busy dating the new guy and sleeping in his room and all. People on her campus knew she was dating but her friends outside which are my friends as well had a very different story in which she showed herself as the good guy in that situation.

4. The person who was completely against PDA because in India it is still a bit of an issue now publicly is making out with the new guy in the dining area , basketball courts etc, nothing wrong in it but just seems so not her. Also the new guy is also a downgrade as well.

I know this much is because i have friends on her campus and my friends say stuff as well even though I have made strict boundaries on not to speak about her but things slip out. It doesnt affect me that much anymore but the issue is this after knowing all this I just feel I dated someone who was literally a ghost because such a radical shift in her personality is so difficult to explain. The innocent honest woman with so much integrity is now someone who just sleeps here and there. This is making me question what even was real to be honest like were those 4 years with her a dream? I also recently after like 8-9 months post the break up am finding it difficult to see her with someone else because I saw a future with her and the cruel part is she didnt care for a second before any of her actions.

My friends on campus or even outside feel she is just miserable and broken and is just trying not to be lonely because I know how I treated her what standards I kept for love in the relationship just feels weird seeing all this. They said she is just filling a void by doing such things.

Its been 10/11 months from the Dday I am doing reallyyyy good than I was before (was a mess earlier) but just these thoughts of what and who did I even fall in love with and seeing her with someone else is holding me back. How did you guys handle these thoughts, do they still come up?