My girlfriend (18f) “cheated” on me (18m) and I don’t what to do.

For some context, I know 7 months doesn’t sound long, especially at a young age, but for another 6 or so months before we dated she was my best friend. So I’ve known her for roughly a year and she’s been the closest person to me for 11 months.

We met because she got cheated on while dating a guy I’m friendly with and I helped her with that at a social event. after that event we’ve been pretty much inseparable, and again I know we’re young, and I know that Highschool, well now college relationships don’t usually last, but I really saw this relationship working out and her being the one. Which is something I didn’t even want while so young before I met her. That part is important because I was also cheated on in my last relationship and a big point in our relationship was that we’d never cheat.

I went to visit her about a 2 weeks ago and I caught her cheating by finding pictures on her phone of her in her bed with another guy (also 18M). After much questioning of her, her friends, his friends, and even reaching out to him, the most I could find was they fell asleep together only once and it was clear he had been into her and not vice versa.

She said he asked to come to her room because his roommates girlfriend was over and he didn’t want to hear them going at it, and she agreed thinking it would be normal because he was in her friend group. But he stayed much later than she intended him to and he got in her bed without invitation and wouldn’t get out. It sounds a little dishonest to me, but I do know she never expressed interest (or atleast online) to him. Through multiple sources I confirmed they did nothing more than sleep just once. I also know it had nothing to do with any problem on my part, the guy is shorter, weaker, and looks like a gremlin, and I’m not a mean person that is being generous. (I’m not kidding). I also treated her beyond perfect, this was the first girl I’ve ever loved and we also had 0 arguments until I found this.

If I wasn’t as in love with her and so attached to her as I was, I would’ve ended things on the spot, but I let us stay together another couple days before finally ending it. My problem has been that she is so remorseful and literally heart broken, and even though we are not together, she has blocked every guy on everything, and expressed how much she regrets what she did. She also constantly tells me she loves me, and how she ruined her whole life, mine, and I am best thing that happened to her, and she fucked up but would do anything to make it right. That coupled with I do still love her, as we’re still in contact, and I miss her a lot, I am unsure if I should get back with her? Or even think about it. If she is serious about her regret and that she will never do that again or anything bad, and change, I do see it possibly working out. I just don’t want to be delusional/manipulated, and would like advice on what to do especially considering she didn’t kiss or have intercourse with him.

Honestly putting the relationship to the side I just miss my best friend. And my friends have given me mixed advice.

Tldr: my girlfriend who I’m really attached to fell asleep with another guy but didn’t do anything else and is remorseful, and dedicated to fixing things, and I miss her and love her still but don’t know what to do going forward.