My 2 "Best Friends" keep making me feel left out. help!?

Well i have well now had two best friends. lets call them Ema and Amy. Well me and Emma were best friends since 6 grade then in 7th amy was new to our school and she became our best friend. We were the bestest of friends. Then now in 8th grade we started to grow apart. Amy and Ema are in cheerleading and i had quit, ever since i quit they have been making me feel like a 3rd wheel. In lunch all the timme they are ALWAYS ditching me. They never invite me anywhere and on facebook they write things on eachothers wall like " you my one and ONLY bestfriend" everytime i see a picture of them both i feel heartbroken everytime that they say their best friends and over eachothers house makes me want to cry. on top of all of that, Amy seems to get mad when im hanging out with Ema. she starts screaming in my face "we dont caree!" and everytime shes not with Ema shes super nice. they talk bad about me at times. I feel like crying everytime i see picstures and videos of us when we were bestfriends. everyday i feel more left out then ever. Ive tried looking for new bestfriends in my school but everyone has a bestfriend and i dont wanna be the mean girl and get in the way of them. Ema and Amy have made me cry twice b/c of things they say to my face. and everyone says that they are being the mean ones and im the one that always forgets them and does everything for them and that they are taking advantage of me and just using me and they telll me to not hang out with them anymore but its hard to let go. Please help me i need advice!