Hi Walitola ,
I would ask your mortgage person who is helping you with the refinance. He would be able to tell you how a short will affect your credit.
In order to get the short approved, you will need to show financial hardship, ie that you will not be able to afford the payments. The bank will then do its own appraisal to see what the value is. The process is not quick so I would contact your current lender ASAP.
Please feel free to call me if you have any questions or need help with comparable sales.