So today my brother (15M) invited friends over in the morning. I (13F) slept in because I was able to and I was really tired. My door was open because my room gets super, super hot. And I was sleeping naked. Because my family doesn’t give a crap, we pretty much just walk around in our underwear at night time, and no one cares. Anyhow. My brother invited five of his friends over while my parents were out, All between 15 and 17 and all male. I woke up to realising I had to hide under my covers because my door was open and I was naked. Two of his friends realised I didn’t have a shirt on because they didn’t see any sleeves on my shoulders and while my brother was distracted they walked into my room. However my brother noticed after I shouted for him and completely went off on them. Telling them to leave and never talk to me or him ever again, because he didn’t want friends that would hurt his sister. They left and he closed my door so I could get up and get dressed. After my parents got back, My mum screamed at him for not closing my door before his friends came over or even waking me up and telling me. My dad said I should’ve at least worn a bra but it’s not my fault I didn’t know they’d come over, and he grounded my brother. I told him I understand it slipped his mind because our family doesn’t normally care about about any of us sleeping undressed and visible, but he still should’ve told me, because if he didn’t notice, I don’t know what would’ve happened. But now he’s sad because his two best friends stopped talking to him. Saying he overreacted and should’ve just let his friends “do their thing”. I feel really shitty like I ruined his friend group. AITA?