The girl I have loved for 3 years loves someone else and I have tried everything I can think of to get over her what do I do?

Why don't you go out with your friends more often to help you get over her. If that does not work, here is what you should do:

take two envelopes, and a couple of note cards. label the first envelope as "your last girlfriend's name" and the other "the better girlfriend". write down everything she was that hurt you on a set of note cards and put them in the last girlfriend's envelope and write down what you wish she was and your ideal girlfriend on the other note cards and put them in the better girlfriend envelope.

It is just a way to insult her and tell yourself you are much better with someone who isn't that heartless. lol just playing.

if these two above does not work, try to go out with a hot sexy woman and post pictures of you too kissing online. And if one day you see your last girl on the street and she tries to talk to you, tell her "I need you...I want you... to get out of my life.