My friend is sleeping with her brother.

Now I can’t physically prove this but she’s confessed it to me that they have and probably still do this multiple times. Sorry this is so long btw but it’s crazy. It started off as a rumor in her family and I only learned about it because me and let call her Molly are so close. Her dad threatened to cut her and him off from him and his money if he found out it was true. One day when I came over I noticed her brother leaving the room I didn’t think much of it because Yk wtv but then I stepped into the room and it smelt hot? Like Yk that after sex air yea… I didn’t question it but later on when we hung out I noticed the behavior that they had around each other they were very playful and I mean…too playful. We had driven over to one of their cousins houses and even he commented on it. Any time Molly got to close to the cousin her brother would step between them and he wouldn’t let them to be alone. The cousin isn’t off the hook either because he made a joke saying “what you think I’ll take her from you?” Molly laughs but her brother doesn’t and instead he gets mad and makes us leave. In the car I ask about it and he rubs it off that everyone is so hard on him and Molly is the only one who is nice so what the cousin said was mean. When we get back to her place mollys dad bust in the door I wasn’t surprised he’s your average white middle age perverted man but that’s a story for another time. He comes in and yells at Molly saying that she shouldn’t be doing anything w her brother and it’s dangerous because AND I QUOTE “I use to sleep with my aunt and it made my family a mess” Stuff like this was normal in their house and like I said i was very close to Molly…this girl has showered infront of me naked. Anyways Molly started crying and yelling at him that nothing is going on. Her dad leaves and I hug her. Then I ask are you sleeping with him. Ofc she denies it first but I’m not dumb….im kinda a butthole for this part but I say “love is love” IK IK SO BAD! Anyways she basically is like yea and it’s so hard to find someone to get this connection that me and my brother have an I love him and just gives me the whole spill about how when it first happened it was a accident they were drunk. But she continues to say…it hasn’t stopped. One night I was spending the night and I guess her brother didn’t know an he sneaks in but Molly tells him to stop and tells him I’m there (I was in her bathroom) he says something then she says I can ask her to go to another room. I step out the bathroom and he looks at me then back at her and Molly says “I told her, she knows” he looks a bit disappointed but I reassure him it’s not my job to judge and walk out the room. (I DONT SUPPORT INCEST OR ANYTHING OF THAT BUT I WAS LIKE 18 I didn’t know what to say!) That’s the last I really heard of it I never dug into it anymore.