I just registered today, because I want to help answer the question.
If you are not worried about your credit, you should stop making payment. If you keep paying, bank may not work with you in terms of short sale or deed in lieu foreclosure. Any of these two will lower your credit.
In the process, you should ask the bank to forgive you the loan(difference). if not, you leave the bank an opportunity to go after you down the road.
If the bank does forgive you, you may receive 1099A, in the eyes of IRA, loan forgiveness is treated as income even though you have never received the money. Two way to get you off:
1 bankruptcy, 2 financial insolvency - meaning - your liability exceeds your assets, such as if you add all your asset say 200k, your liability including this loan is 300k, they forgive you 50k, you don't owe any taxes at all. Please feel free to call IRA and they can explain to you better, although be prepared that everyone may give you a different answers, but you will get it right from IRA or your CPA.
Most likely they will not go after your current house, because if you file bankruptcy, most counties in NYS have exemption up to 300k for a couple.
Best luck to you and your family!