I'm so sorry that you had to go through this. I recently got out of a toxic relationship as well and while I have my suspicions that she cheated on me, they were never confirmed. All I know is that she did a similar thing with flirting and sexual jokes to a lot of other guys who only talked to her for one reason. There was an instance where she slept in a bed with another guy and she was practically naked and that day I ended up stealing the guys cigarettes and alcohol and got so drunk that when I came back to her that night I had to go to the hospital because I drank so much. That was right before I went to the psychiatric ward for attempted suicide. That was in February and I only just broke up with her like three weeks ago.

I know how you feel, at least partially. I still feel ashamed of myself for some reason like it's my fault she acted that way somehow even though I know it's not. I get a panic attack every time I see her or her friends on the street. I have that thing where you can see her with another guy especially because her social media has been filled with sexual comments back and forth with dudes. It's so painful.

There are times where I just need to go for a walk and cry by myself. For the most part though I try to surround myself with friends and positive people in my life. I love to read and write stories so I spend a large amount of time doing that or studying English college lectures on youtube. I also play guitar and the sheer passion for these things gets me through each day. Positive music is key to uplifting yourself! Take those joyous victories everywhere you can! Alcohol will only make everything so much worse.

I also recently deleted all the pictures I have of her on my phone but I haven't gotten to my computer. I took all the things she gave me and put them in a bag and in a container so I can't see it all. I unfollowed her on facebook so I can't see her posts or those other guys' comments anymore. I'm just trying to focus on what I'm doing. I often get consumed with the thoughts and memories, but when I notice that happening I just remind myself to take a step back, stop thinking about what she's doing because it doesn't matter anymore, and focus wholeheartedly on what I'm doing, the goals I have in my life, and taking steps to accomplish what I can for myself.
My heart really goes out to you, man, and I hope this helps even if just a little bit.