Mmkay so i need advice......?

i just acted like i was asleep for 2 hrs. and my friend was saying horrible stuff about me...like: i am a man, i poop my pants...ect. i am the only conversation peice to have with my sister and her friend (the same from my last question) and this is not the first time. she does this behind my back also so i do not really feel like confronting her about it. how do i get over this? my sister and her friend did not go for or against anything she was saying so that kind of hurts because it is my own sister. (we are only 14mnths. apart). Also sometimes i get the notion that my sister likes my friend more than she likes me and my friend is starting to use me