Found out my ex has someone new. Help me get through this?

Please see my previous question for more detail about my relationship with my ex.

It hurts because he would talk about how “disgusting” it was when someone dated someone else so soon after a break up. Now, only after a week that he messaged me “Know that I am waiting for us in the future. I love you, I will do anything to be with you…” I heard from my friends that he was being friendly with another girl. I don’t know what to do. Help? Moving on is so hard to do, especially in a small city and living in the same dorm.