Replying to Slept with girl and she keeps having me chill with her even though she has a 'boyfriend'

This girl dragged me into her bed a couple nights and I asked her out I had too much money and wanted to spend some of it. Then she said she was in a relationship even though her boyfriend lives out of town and I see her more than her actual boyfriend so I am her 'friend'. Anyways there are always girls giving me attention but they always sleep with me and say I am their friend and I am ok with that.

However this girl wants me to take hallucinogens with her boyfriend and this other girl that likes me. I have slept with this girl while she has been together and she didn't tell me that she was dating this guy.

Haha why does this have to happen? Should I just play it cool?