I feel like my confidence level is waaayyy down. A girl from my school, I thought she was my friend.read below?

Okay, so i go to a school that I transferred in at the last few months of school. I was soon invited into a small clique of four girls, not including myself. I knew two of the girls in my group, mainly one. Let's say her name is Marie. Well, one of the girls is very, very jelous of me and Marie's friendship. She is a bully already. But she is trying to get Marie not to like me anymore or be my friend, by saying rude things like how annoying my voice is, ecct. But Marie and everyone else has stood up for me. Still, I can't help feeling a bit down. I really can't stand bullies. =( What can I do to help me get through the mean glances and all the talk behind my back by that one girl? Thanks for reading!!