It's a Chinese xianxia. That alone should answer your question. But if you still don't know the answer, yes. He has sex with everyone, including his sworn older sister and he raped Medusa.
I don't think he had sex with anyone else besides Medusa and that wasn't really sex either. Kinda rape but also not a rape since he didn't do it on purpose but yeah, I don't remember him doing it with anyone else. I might be wrong though
He has sex with at least 3 people that I can recall, Poison Fairy, Medusa and Yun Yun from Misty Cloud Sect
Eh? You ask me for chapter... I don't remember. It's been so long since I dropped the novel. As for sworn older sister, I'm talking about Yun Yun. In the manhua she didn't have sex with Xiao Yan, though.
Well he's only got two wives... Wait I only remember him have sex once... Oh my God... Uh my 2 favorite girls didn't make it... Damn it I should've forgotten... So sad...