I dont know what to do!!!?

Ok, my best friend since i was 5 got a new best friend. That was in third grade. Now that girl hangs out with my bff left and right. I have the feeling that she might be trying to get rid of me. HELP!!! Oh, and it looks like she doesn't like me either. When I say " It's comlicated" in a convo. she always says " I'm not a baby, and I'm not an idiot, so tell me. Sometimes I wish you would trust me like im my age." She hates me! And she is really, really mean to me. :( What should I do? I tried talking to her, and I tried telling my best friend, but that just made it worse? What do I DO?