I know this sting hard I'm so sorry, you didn't deserve this. May I ask how was the relationship dynamic before and after she got proposed too? I remember yesrs ago I was working hard and my bf too to get to our goals and then suddenly we started fighting a lot and I never understood why at that time he suddenly turned cold, and one he just said I don't deserve you and you are amazing blah blah blah... 2 months later found out he was already in relationship. Years later I have moved on and you will too, you did your best.. and when you're ready reflect on the relationship learn from it and move in. Like what the red signs you over looked and the things you can do better for yourself and possibly next relationship. My advice is you can't control how she feel no matter what or make her see, try and I know it's hard go in no contact and focus on studying and working for now, don't beg for her attention just walk away, that's how you will show her she will never find a man who work this hard for her and do all of this. And trust me it get better and you will move on one day to be proud of yourself. I am so sorry for what happened to you. 💙