She was like my best friend, so how do i get that again?

I don't know why she acted like that but I would ask her why she said those things to you. Tell her that you want to be friends again but you don't know if you can trust her and that you are hurt from what happened. The how will just come if she wants to be friends again. Just remember that if she doesn't want to be friends then just let it go if you push it nothing good will come of it. Just be nice to her when your around your friends to settle the peace.