cw: sex topics. Hiii, so I (18f) recently moved to a new city to live with my sister (28f) for college. Things have been going okay but it's difficult for me to make friends or date since I'm still very new. Today I met my sisters' boyfriend (28M), they're both really nice but we met at a party with a bunch of drunk 30 year olds and it was highly uncomfortable for me, so I'm thinking this might be ONE reason that my panic attack started last night.  So after we went home she didn't tell me she actually wanted her bf to stay the night. They made it seem like he was just tired and needed to sleep, so I honestly didn't think they were going to be fucking. Probably was kinda naive but I've never had a "roommate" before. They weren't incredibly loud but it was 12 am and I could definitely hear her bed because it's against my wall.  I'm not really sure why it triggered me to have a panic attack (past sexual trauma maybe?) but I had to sit there and cry while listening to my older sister have sex. I feel like if this was any other type of roommate situation I would be okay, but I'm already uncomfortable around men and sex is just a topic that she and I have never really spoken about. It was definitely expected, but still a shock, I think. I tried putting in heaphones but it had already pretty much traumatized me at that point. 

Like I said earlier I don't really have any friends or SO to go to spend nights with so she has time alone with her bf. I don't know how to approach the situation. I have severe anxiety but I haven't been able to get therapy/medication since I was 14/15 or so, so until then it seems like I'm just gonna have to rawdog life/panic attacks lmfao. I want to talk to her about it, but also this could just be a one off type of thing that won't happen again. I don't know. And if I do talk about it, I want to be as polite and understanding as possible, but for some reason them having sex like that just made me feel unsafe, and being at that party earlier was just stressful for me. 

Part of me is wondering if it's just my brain associating my older sister with purity, maybe subconsciously I'm just jealous, but also the fact that I only met this guy today and had to hear him fuck my sister? I'm not sure but I'm not having a good time. Any advice would help, whether it be about dealing with the panic attacks or on how to talk this out with her. I just don't want to be nitpicky is all. 

TLDR: I met my (18F) sisters'(/roommate) (28F) boyfriend (28M) last night at a party I hated and had to listen to them having sex once we got home which caused a massive panic attack.