I'm going to give an ex the cold shoulder treatment
What did she even do to you?
She broke up with me twice so now I will ignore her as revenge.
Well, she is your ex now so it's wise to just stop associating yourself with her. Continuing to mull over her will just bring back more wounds.
I just really want to hurt her since she hurt me so much.
While you have the right to completely break it off with an ex, it's not healthy to obsess over it. They are probably very over you, so I think you should do the same. What if a new relationship is waiting right in front of you, and you don't realize it because of your ex?