I don't want to lose my best friend
Why not?
Because they were there for me during difficult times.
I think that sounds hard. It's natural to not want to lose a supportive friend. You should talk things over with them.
I don't want to forgive her when she was rude to me.
You should communicate with your friend if she did something to hurt you. Holding grudges will only ruin your relationship when there's a chance it could be repaired.