Hey. So you realized that what you liked about Catherine wasn't in fact Catherine but the idealization and "ghost" that Catherine was in your mind? Perhaps you are realizing that you don't like Catherine as a person but as the idea and that maybe it's time to move on and leave the shadow that she left in your life. From what I know about this whole story you keep thinking about her and idealizing that you guys will meet and things will turn to be like a fairytale and that doesn't happen. You need to get closure or something. Do you really think this is going somewhere? - ask yourself that. I this battle worth it? Is she going to look at you and appreciate you? - I mean if she hasn't already what do you think it's going to change that?
I think you NEED/HAVE to get in your mind that this isn't working and that you've already wasted too much time on it. Go out, meet new people and enjoy. Stop making idealizations. I know it won't be easy and that it probably hurts but people have to learn to let go sometimes.
You seem like a good looking accessible guy and I think that you won't have trouble meeting people. Work on your self-esteem, enjoy being young, focus on school and gradually get yourself out of that depressive cycle that revolves around this person/the idea of this person. You don't have to live in your past forever, you know? There's more than life even if we at times don't see it.
I've mentioned before that a counsellor would be ideal so that you can talk about it and realize things that you won't normally realize by yourself or that take you longer to realize. If not maybe start writing a journal and burning all the memories, contacts, things that remind you of her, etc; at least until you can be strong enough to confront it without falling to pieces and getting into a numb stage.
Good Luck.