If you are craving sweets then eats some fruit that you have to eat one by one. ( like grapes )
I agree with Barb, get rid of it.....it will actually make you feel in control. If you polish it off you will not like how you'll feel at the end. You could eat a piece, but i guarantee the rest will not sit in the fridge for long. Sorry if that sounds negative, but from experience I know. Its been 10 hours since your post.....did you eat said chocolate bar?
If the chocolate in the fridge is causing you so much anguish, you should get rid of it (not by eating it, either). If there are foods you can't stay away from, it's best to not even have them in the house.
The alternative is to go ahead and have a SMALL piece of the chocolate, just to satisfy your craving. It only takes a couple of small bites to satisfy the brain, if you let it.