I am so mad my ex is dating the guy she said not to worry about!
What did your ex say to you to get you to not worry?
She just said he was a casual relationship and that I didn't have to worry.
It makes sense that you would be upset with your ex for lying about this situation. If she told you not to worry about the person than she should not be about to date them either. It is important to realize that not all relationships end up like this, keep your head up!
Its like you don't know how the dating scene works. I'm going to tell her how this makes me feel and how she better get out of this relationship right away. I expect her to have common sense, if not I will crush her.
It is wrong that she lied to you. But you are broken up you cant expect to control who she dates. You should move on in your life.