I can't sugar coat this, on the surface, when you have to cheat during an open book exam, it's the sort of thing that makes me say, do something else for the next five or so years, because your medical career might not be over, but it is more likely to be in stasis. An infraction like this makes you look note merely unethical, but lazy as well.
Are you FR, SO, JR or SR? The older you are, the worse a reception you'll get from Adcoms.