Try not to be so hard on yourself.

As Puzzled said, fantasies are only fantasies. And let me tell you from personal experience, hating yourself because of something like this doesn't do you (or anybody else) any good. Do as the Buddhists do. When you have these fantasies, simply allow yourself to become aware of them, but do not judge them. Simply observe them, and allow them to flow through you and out of you. Then go back to what you were doing. The most important thing is not to judge yourself. Just observe, like a scientist.

Shine On,
Enigma