My ex posted showing herself off and followed a new boy after having a go at me for following someone ( how to stop loving someone and thinking about them so much)

I honestly don’t know what to do anymore.
My ex cheated on me a few months ago with a guy she worked with. I found out because someone else told me, rather than her telling me herself. I tried to make things work afterwards, but I couldn’t get over what happened. I kept getting angry and upset about it and constantly thinking about all the things I’d found out afterwards.
Eventually things ended properly.
I know I wasn’t perfect in the relationship either. I could be horrible, snappy and say things I shouldn’t when I was angry. I’ve taken responsibility for that and I know I need to change those parts of myself. But I also can’t pretend that being cheated on didn’t completely fuck with my head.
Recently we’ve been completely apart and she barely gives me the time of day anymore. She says we’re not good together and that she doesn’t want to get back together.
Today I saw she’d put up a new Instagram highlight, basically just pictures of herself in gym outfits showing off her body. Then I noticed she’d started following a new guy and he follows her back.
I know technically we’re not together anymore. I know she can do whatever she wants. But seeing it absolutely crushed me.
What makes it worse is that she got really upset with me previously for following a girl who’s just a friend of mine and who I go on nights out with. So seeing her doing this now makes me feel incredibly angry and hurt, even though I know I don’t have any right to control what she does anymore.
And that’s the part I’m struggling with.
I still fucking love her.
I don’t know how to just switch that off. I don’t know how someone who was such a huge part of my life can suddenly become someone who doesn’t even want to speak to me, while I’m sat here feeling physically sick over things she posts online.
I actually had a panic attack at work this morning because of everything going through my head and had to go home. That’s how badly this is affecting me.
I know people will probably tell me to block her, delete her, move on and focus on myself. And logically I know they’re right. But emotionally I just can’t seem to let go.
I’m angry at her. I’m hurt by what she did. I’m angry at myself for the way I reacted to everything. And despite all of that, I still love her and part of me still wishes we could somehow fix everything.
How the fuck do you actually stop loving someone?
Because right now I genuinely don’t know how I’m supposed to do it.