Let me start with this: You will, eventually, get over this. Why not now?
Love is a strange and wondorous thing. If you love her, but she doesn't love you back the same way... can you be happy with that? From your comment it sounds like the answer is "no." Okay, fine. It sucks right now, but ultimately, you will be happier to move on right now, rather than spiral the drain of dispair over this.
There's a quote attributed to Buddha: "Holding on to anger is like grasping a hot coal with the intent of throwing it at someone else; you are the one who gets burned." So let it go. Take this as a lesson learned, another turning point in your life.
For now, live your life. Look around, find something that makes you happy. Is it sports, (playing or watching), or playing poker with your friends, raising your dog? Whatever it is: do it. Got nothing? How about a job? Pour yourself into your work, and excel at your job. At least that part of your life will be more secure, people will complement you on a job well done, (and come what may, having a few dollars in the bank is always a good thing). Regardless - it will make you happier, which, in turn, makes you more pleasant to be around.
And guess what? By and large, people prefer to be around pleasant people... opening the possibility of a new girl coming into your life.
Don't mope! You're alive, there's no asteroid or aliens coming to wipe us off the planet, so go out and enjoy yourself. Heck, you're free to flirt with any pretty girls you see. Girls are everywhere, and oh-so-fun to look at! (Just don't be creepy about it.) Plaster a smile on your face, and after a while... it will become a real one.
