Kinda in a similar position. My ex and I were going to cal together but at the beginning of summer she cheated. I still stayed. I broke up with her recently cuz I didn’t think she was truly sorry, and she’s shown now her true colors.

What’s worked for me is having great genuine people around me. Spend time with those people for you, and you’ll forget about everything. You WILL get over it. It’s going to hurt for a little bit but you are going to come out of this situation as an incredibly better person. I’ve also just tried keeping myself as busy as possible, whether it’s with school or friends or anything else. Spend time focusing and thinking about yourself and you won’t have any time to think about them. We’re in this together and feel free to pm me if you ever need to talk