Is AUTHOR wrong in the post ? POST : (I know I’m already the asshole for the cheating bit, I’m just trying to make things right)

I got involved with a guy (he initiated) in one of my classes. I heard him talk about his girlfriend before but it had been a while and I assumed he broke up with her. When I found out he didn’t, I still stayed. I’m not in the best headspace and I wanted someone to care about me.

Finally, the guilt got too much and I tried to break it off. He told me that he was going to break up with her, he loved me more, etc and like a moron I believed him. Then once my guilt manifested into not being able to have sex with him he broke it off, never having broken up with her.

Fast forward to now, I am a wreck. I can’t sleep, every time I see him I want to vomit, he told all my personal stuff to our mutual friends on campus and now I have no one. I found his girlfriend on Instagram and I am thinking of telling her. “The truth will set you free” and all that. I want to put this behind me, I’m just worried about my motivations. A part of me does want revenge, but i mostly just want to stop punishing myself on her behalf and let her do it herself. Or she forgives me.
(Note: I’m not going to tell her anything along the lines of “oh I feel so guilty pls forgive me” I just planned on telling her he cheated and I’m sorry she had to hear it from me. Maybe say I came to her because the guilt got too much just so she doesn’t think I’m doing it maliciously)

So, render your judgement reddit. Will I be the asshole?