I'm a *** hole and have lost at least one good friend because of it. How can I change?

I admit Im a straightup . My myspace profile song is "hole". I just like being an , and its extremely easy for me. I love making fun of people and I love being cynical. But deep down inside I do care. But almost all my friends are and Im comfortable around them. But I lost the girl of my dreams because Im an hole. She was my bestfriend and my dream girl, and now Ive lost her. How can I change? Im just so easily annoyed by stupidity and quick to make hurtful remarks.