First, as Mickey and JP advise, you need solid numbers. Not just whether you're upside down, but by how much.
Second, if you are upside down, do you really, really have to sell? If not, don't. In fact, even if you aren't upside down, do you really have to sell?
Third, if you do have to sell, can you maximize the value of your property so you're not upside down? That means adding value to the property. It also means structuring terms and conditions so you come out even or ahead. A lease-option is one option to consider. There are others.
Finally, a short-sale should be your final choice, only when you've run out of other options. It's often a long, painful, and very uncertain process. And it'll really damage your credit. Not quite as bad as a foreclosure, but bad enough. Don't do it unless you absolutely have to.
Hope that helps.