It was wrong of her to cheat on you, and if you decide to break up with her, it will be her loss. However, it seems that you really care for this girl and that you are also hurting yourself by not communicating with her. If you can stand looking at her, try and speak to her face to face and hear what she has to say. I’m not saying anything to excuse her behavior, but we all mess up at some point, sometimes hurting those we love. If you cant forgive her after the talk…then you’ll know that you def. Made the right decision. Good luck.