I've lost my bestfriend?

okay, well we were sitting in a circle at recess with a few other people, and me and my other friend were showing this a thing, and she thought it was stupid. She has to always say negative things, its really annoying. Then, somehow we started talking about how scabs randomly formed on your skin, and i said that they dont, and my other friend agreed with me. And then she says that they dont form randomly, i dont get her. But it was on for a while, and its actually worse then what it seems like. Then she called me stubborn, and act like a knowitall, it seems as if everything she says it right, and everything i say is wrong. I say to her that maybe i dont have to agree with everything you think, and its only your opinion. So she goes, omg, you're so immature! and walks off with my other two friends, in in those two friends, one of them is my bestest friend. They weren't even involved, they were only sitting there while we were arguing. and i cant believe my BESTfriend is on her side now. Since then i haven't talked to her for one day, and i haven't done anything, until today i found out that she turned a lot of people against me. i am really angry at her, but i still want her back, because shes a really good friend. but not at the moment obviuosly. but in the past shes been a really reliable friend, she always stuck up for me, and seemed like the only person i could talk to. but now shes slightly gone a bit.. mean. And we were going to go to boomtec (a disco) together, and now she decides to go with my BESTfriend. i cant believe this, someone like her doing such a thing. I said sorry, but she hasnt replied to my message yet. Please help, what should i do? i dont want to not be friends anymore, so dont say something like 'dont be friends with her anymore, get new ones.' because our fights dont last very long, but i always need to find a way to make it over, and i dont know what to do. please help.