Advice?!

I recently became friends with a girl who has been my friend on all my social media for years we live in the same area and know a lot of the same people but we are 4 years apart..she's 30 I'm 26. She has been coming on to me lately and wants to have a 3 some with me and her bf who btw has told me is gay as well. He supposedly had sex twice with the same man who is a transvestite so he still has a penis which to men means her bf is gay or maybe bisexual. They recently just had a baby as well like 5 months ago. I am not attracted to girls in that way but always did wanna have a 3some just cause I'm curious and mainly watch and be performed on I wouldn't do the girl or anything tho. Now I wouldn't had felt any type of way but she knows she told me he's basically gay and now I feel kinda disrespected knowing he has sex with men and unprotected as well he has given her STDS. I kinda wanna distance myself but I feel like I'm in too deep now and I'm kinda embarrassed 😩. I still like her as a friend but don't know how to address this properly. Any advice? And please no judging or you can simply read and move along thanks 🙏🏼