How tf did i get cheating rumors

I'm like confused cus my relationship with my bf is a secret irl since he's in the closet except for a few friends he has but like I had been in school these past few days and ain't even chatting with anyone. Dude just DMed me and said "ppl say ur cheating but if you wanted to cheat with a woman don't, just say you like a girl too. I don't mind being in a throuple" LIKE FIRST OF ALL POOKIE IF I DO THAT, BEAT THE SHIT OUT OF ME and 2nd I'm not even poly but that's wild. Anyways I investigated further on how and it was cus i hung out with my old friend who's a lesbian and we ate together for lunch