My friend is in a love square and I don’t agree

So I’m not going to put the real names in here because of privacy but my best friend Sarah who’s 24 works with this guy named Larry who’s 42 and he’s married. Sarah and Larry mutual work friend name Hayley who’s 18 and she’s in a relationship with her baby’s father. Now Larry has been flirting and send raunchy texts and pictures to both Sarah and Hayley and my friend Sarah and her friend Hayley have also been sending him stuff back. And Larry pays for stuff for them like to get there hair or nails done and dinners and all kinds of stuff. Sarah and Hayley come over to his house once the wife leaves for her night shift at the hospital. Hayley has been sleeping with Larry several times and Sarah hasn’t crossed that line with him yet because Larry and Sarah know it will make Hayley jealous. Larry and my friend Sarah have crossed some lines. Larry’s wife is getting suspicious and I feel really bad because they have beautiful kids together and his wife is beautiful and his daughter is as old as Hayley they girl he’s sleeping with and my friend Sarah is heavier set but she’s been losing weight and looking really good and so she’s been getting a lot of attention and she said she like the attention she gets from Larry but Larry is a married man and he’s sleeping with her friend Hayley and frankly I completely disagree with my friend Sarah’s choices I told her there’s plenty of men out there that aren’t married she can get attention from. I just really disagree with her and it really bothers me I have shared that I disagree with her but she’s still crossing lines and brags about how she has a sugar daddy. I have been thinking lately about randomly messaging the wife because I know I would want to know if my husband is fooling around with two women what do y’all think I should do? Any advice?