"Fat girls" vs. "Skinny girls"

Alright, since we're here and I have this.. here's a question and it's not meant to hurt anybody or seem like I'm attacking anybody, it's just questions. But why do larger women absolutely despise skinny women? I belong to a MMJ chatroom site, (one of many charities I belong to). While in the room approximately a month ago, I was called a "slut" by a larger woman, for merely being beautiful and confident with myself on webcam. Why? Yes I have had 4 children, yes I am small, yes I am gorgeous. Does that mean I'm smarter? No. Does that mean I'm ignorant? No. Does that mean I don't have feelings like that of a human being? No. Does that mean I hate "fat" people? No. Does it mean I'm bias? No. But if it is so wrong for one to be bias.. why is it, y'all are doing it? Now can we please stop hating on the skinny/large girls? Thank-you!