Law School Hookup Gone Wrong

Started law school this year and I'm still figuring out my footing here. No real girlfriend, just dating around for now since everyone's so focused on studies and career. Met a girl named Casey in my Contracts class, seemed like she was into me from the start. She'd always sit next to me during lectures, send flirtatious messages about assignments we were working on together. One night after our study group got out, I invited her back to my place under the pretense of a last minute cram session before exams. We locked ourselves in my room and didn't come out until morning. It was wild, no condoms, just raw sex from start to finish for hours, both of us getting off on the taboo rush of it all since we're both 18+. Had a brief moment where I wondered if this was too much but... it felt too good. Ended up talking about law firm recruitment and summer internships afterwards. She mentioned she had a boyfriend back home and wasn't looking to complicate things here at school, so it'll probably just be this one time thing between classes when we can sneak away from the dorms for a quickie session in my room. But now I'm left wondering if I did something unethical here. We're both studying hard for our careers and she's already made a life back home, am I taking advantage of her being new to this environment? Is it fair that I'm exploiting my position as her classmate to have casual sex with her, even though we're both adults? Don't really know what to think about all of this. Just wanted to get this off my chest.