The estimates on this and other sites are fun to play around with, but not always that accurate. Make an appointment with a good Realtor who can give you an accurate idea of what your house could fetch on the open market today.
If it's worth less than you owe, then your options would be to:
-Rent the home out and try to qualify for a mortgage to buy another home
-Sell the home and write a check at closing to cover the shortage, then move on and try to buy another home
-Try to do a short sale, then rent a home elsewhere for 3-7 years after which time you can be eligible for a mortgage to buy a new home
Hope this helps!