Please start by reading your contract. Chances are it will explain whether the $5000 is part of the 3% or in addition to. You may also find a legal way out without penalty. If you don't feel confident in understanding what you signed, have it reviewed by an attorney. They may save you thousands, but time is not on your side. Get in front of one tomorrow.
If this is just a case of buyers remorse, you are in good company. Many buyers get cold feet, but when the options are weighed, most will move forward. You have to live somewhere.