Came across my GF dating profile on a app and I might break up with her.

So basically this girl and I met on this dating app maybe 2 almost 3 years ago. Most of the time I’ve known her, she’s always liked me, but I curved it because I was still stuck in a relationship of my own. Maybe like a month or 2 ago, I finally gave in and decided to get into a serious relationship with her. I’ve met her family, and some of her friends already so why not? Now I’m 19 and she’s 18 and about to be 19. Like 3 months ago in February, she told me she slept with her friend’s bf in high school because she didn’t want to be friends with her anymore and she always had a crush on him (dude looks like me apparently). I was never able to shake that because it just sounds messed up as hell and kind of whorish. Even though we weren’t dating, we were still friends and FWB at some point and I was just been disgusted even to this day because I knew she wasn’t single herself with another BF. I already have bad trust problems from a previous relationship so this is slightly a problem. She says they only had sex one time but to be honest, given she took the dude’s virginity, I call bullshit. Not to mention, the dude lives around the corner from her and I’m like 20 miles away from her house taking public transportation for nearly 4 hours a day. She also told me this information after we had just finished watching a movie she paid for tickets for. Who she had sex with in the past is none of my business unless it poses a health risk to me. But given the circumstances, I can’t help but think she’s done other dudes and friends just as dirty. Now, I am currently running out of space on my phone. I used dating apps in the past (that’s how we met) and never really went back on the app since like a year or so. I was going to delete but with androids, you have to hold the app and then click delete in the top right corner. I instead just tapped the app and opened it accidentally. The first profile to my amazement that pops on my screen is her. A bio, current age, location, and “dating/friends” included. She also had the audacity to post a photo with her and just my pants and shoes in it. Usually, I let a lot of stuff go but this one kind of pisses me off to the point where I think I want out before I start my college semester and get into another bad depression state that fucks with my health and well-being. My female friend (we’ll call her C); I told her everything and she thinks I should break up with her immediately before I get hurt. Haven’t really spoken to my guy friends about this as she’s been occupying most of my time lately but yeah. What do you folks think? Should I break up with her straight up or explain to her the issue and try to work through this? I’ve known her for almost 3 years. She’s been a good friend to me despite all that above but to get someone in a relationship that they’ve been reluctant to get into for 2 years just to cheat on them is an easy “I don’t ever want to see you again” type of thing. What ya’ll think?

TL;DR: I have terrible trust issues from a previous relationship and my girlfriends current and previous actions make me want out.