Boyfriend's extremely sexual conversation with female roommates/friends

I know some of you have read my posts. I'm dating a guy with all female roommates. He lives with 4 girls in a 3 bedroom. He's the only one with his own room. I've honestly am trying to get more comfortable with them and get to know them. They're all just so rowdy. Especially Jan (his best friend out of all of them since middle school. She has autism). But fone to find out.... they're also extremely... Dirty. Mainly when Jan isn't around. But yesterday they were all talking Dirty with my boyfriend and my boyfriend said "Jan listen to music. Your ears are too innocent for this". But when I first met them Jan literally got drunk? One of the girls(Nina) was talking about in middle school how she got caught behind the bleachers with her boyfriend and him all in her butt.. My boyfriend goes "Wait! You were having anal at 14?!" She goes "No no no. Like his hands were grabbing my butt". Then they talked about Brazilian waxes for like 20 minutes. Then they talked about the prostate. Jan's literally listening to music eating potato chips. They got on a conversation about my boyfriend when he was 16 he experimented with his friend at a sleepover. He said that night was when he found out cum in you eye does burn. Then Nina says "I'm so sorry Riley (me). You look so disappointed in us". His other friend said "Rileys looking like she needs to tell our mama's on us". Idk how to act in these conversations! I'm not that openly sexual and I didn't know my boyfriend WAS