So I’m losing my best friend to this girl I hate and that hates me to witches. Her best friend, my best friend used to hate her SO much last year. I mean she used to talk a lot behind her back and now everything changed. They are closer than ever. Even closer than me and my best friend and I miss her.

We haven’t been talking a lot while they are texting each other 24/7. She shows her that she loves her like she posts stuff on Twitter or Facebook. Stuff that she never ever tells me. I’m jealous yes and sometimes I get those moments where I think my best friend is lying too. And she's ashamed of me because she is the miss wow at school and I’m just a normal girl, unlike her best friend, she's really popular too and plus my best friend is believing rumors about me like What?

A best friend should believe in you, not in a rumor. Anyway what do you guys think I should do? The last thing I want to do is lose her she means so much to me.

It's really hard reading your "run-on sentence" question. It would be easier to read with some periods at the end of each sentence!
I would start looking for some more friends. This one is causing you heartaches, and headaches. Smile, and others will want to talk with you.
A good relationship needs honesty, respect, caring, and a willingness to talk about anything. This relationship doesn't seem to have any of these things. Good luck.

You are way to dependent on her being just your friend while she has many. Make more friends besides her.

You can have more than one friend and so can she. Make more friends.