I know it's obvious but help!!!

So my friend, husband and I were drinking one night and got pretty messed up. my friend passed out on the couch and i went upstairs to sleep. My husband continued drinking bc our neighbors were out and drank with them. I woke up bc i heard a loud noise and my husband came to the room in just his underwear so I went downstairs to see where his clothes were, they were in the living room and I see my friends underwear off but her pants were on. So I asked if they fucked and she said no. I went back upstairs to process what I just saw and she came upstairs to my room to ask me what I was thinking and to just say what's on my mind and I responded i did I already asked u downstairs what I was thinking. she responds with I don't know y this always happens to me and tells me not to misunderstand the situation. I say but y the fuck is ur underwear off and she says it comes off Sometimes when she sleeps. what's funny to me is this is like the 4 time she slept over and her underwear never came off before. my husband says nothing happened I don't believe them, opinions please.