Please don't hesitate to call or email with further questions. Good luck.
A short sale will impact your credit but how significantly it will do so is a case by case basis. I did help one person short sell there home and they never missed a payment. They had a loan through their credit union and agreed to some sort of payment on part of the loss. Ultimately it only affected their credit by 40 points.
Contact a local Realtor in your area that specializes in short sales. They should give you a free consultation and point you in the right direction.