I sort of sent a mean/nasty email to a girl I know?

You stop acting like a kid. First of all, this is what happens when you let someone else do your dirty work for you. Second of all, not only were you too scared to tell her in person, but you were to scared to even sign your name on the email? Grow up, if you can't say something to someones face, you should keep your mouth shut. Email is a cowards way to say what they want to say, but even most cowards will at least sign the email!!! Grow up. You are ridiculous.