Most Helpful Girl
If you honestly want to get over her, then you have to create some distance. I know it would be difficult, as you say she is your best friend, but distance is vital for tempering these feelings. You can't put an alcoholic in a bar stool and expect them to mind themselves. Start spending more time with other friends, taper your conversations off so that you aren't talking to her as often, start talking to other girls.
Who knows, with a little distance, she might decide that she wants to get closer to you. If not, that's great, too! You are making a conscious move towards your future, and that always pays off better than spinning your wheels where you already are.
Most Helpful Guy
I can feel where your coming from. I had a girl who i had a crush on but it was mutual. Eventually we did it but never dated. Even my trying to once or twice to get her to go out. Best thing you can do is move on. Look around you there's thousands of girls you see everyday. Talk to them get to know them and see what their all about. 2 things will happen. either the girl your freaking over will get jelly and get in on the action or you will find someone else that's better. Either way its a win win and far better than doing nothing and just freaking over something that won't go through. Good Luck!!!