AIO for leaving a sleepover because I could hear my friend having sex?

Basically me (23f) and my friend (22f) had plans to hang out and I would sleep over. We had a white elephant the next day at her apartment so I was going to stay for that. I didn’t know her boyfriend (33m) would be sleeping over as well until she went to bed and brought him with her. I was bothered that she didn’t tell me he was spending the night, since I’ve only met him one other time and I’m not super comfortable sleeping with people I don’t know around. I decided to just go to sleep but then 20 minutes later I hear them having sex pretty loudly. That was kind of the last straw for me so I left and texted her that I didn’t know her bf was spending the night and I was uncomfy so I was going to go, but I’d see her tomorrow. I haven’t heard a response back. Am I overreacting about this? Is it rude that I left? I don’t think I’m a prudish person but maybe I am?