I'm going to call my brother's girlfriend out for her behaviour
What did your brother's girlfriend do to you?
She was rude to me and I'm so so angry at her.
Forgiving others allows us to overcome feelings of anger, bitterness, or revenge. Talk to your brother's girlfriend and see if you can come to an understanding.
I'm afraid doing that will make her think she can get away with all this. Am I just being too worrisome now?
I know you just don't think it can be done, but talking will just help in most cases get you what you want. No way will she think she is getting away with anything in that way. It will help get along with her, just use the most tactful words and no anger.