Dude. Break up = she's not yours. Get all reminders of her out of your life and close all doors.

How did you find out about the "boy toy"? However this happened, you need to make sure it doesn't happen again. You're not still in contact with her, are you? If so, cut her off.

Tell everyone you know not to mention her.
Don't look at her MySpace page.

You've got to give yourself a chance here, Tommy.

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I think all women really want is to be proven wrong about men.