talk to your mortgage bank and ask for modification of your loan

Tell them that you are going to default if you do not receive any help from them. It might lower your interest rate to 1-2%.  It may require you to make minimum interest payment and job hunting.  Someone in the similiar situation got his interest rate down to a bit over 1%.  One difference is that it is not upside down situation.  Anyway, try to talk to the mortgage bank before going to default.  Good luck.