I’m sorry that you are hurting. It sounds to me that the real reason he doesn’t want to pursue getting back together with you is because he’s met someone else. If someone truly wants to be with you, they will (no excuses). It may not feel like it now, but you will be okay. I’ve had my fair share of heartbreak in life. None of us are immune to it.
I suggest concentrating on your studies, focus on the things that bring you joy in life, exercise, and eat as healthy as possible. It may take time, but focusing on being your best self is the best cure for heartbreak.