I really really dislike my 'bestfriend'... maybe even hate her
She is your best friend, though. Why do you dislike her?
You have no idea how arrogant and annoying she could be
It is understandable not to like when you best friend acts arrogant and annoying which you may not like them anymore. But you should not hate your best friend. You should talk to them on the way they act.
I don't want to. I want to spend my life without her.
But she's your best friend, is she not? Friends shouldn't be fighting or hating each other, so I believe you really need to talk to her to try to fix your relationship. This may just be a bump in the road, and you wouldn't regret your attempts at keeping your friendship alive!