You are not pathetic. When someone suddenly cuts themself off from you, or leaves without proper explanation, it leaves you with the most helpless feeling. Like Ringo said, get stuck into all those opportunities you have ahead of you.
This time last year, i was in a similar situation, i needed to revise, and felt I couldn't, because of the state of my relationship. But I knew i didnt want to be left with nothing at all, so i threw myself into college work. For me, the determination and drive to do well despite feeling like i had nothing, landed me with A grades, and even a nice 100%.
So get revising! Much luck, and hugs,