You asked this as a separate question as well.
Your alternatives are
* to short sale the house, and negotiate the lower amount that the lienholders will accept, with you possibly paying the difference,
* accept the possibility that the lenders will pursue you in court for the differences in a foreclosure, or
* file for bankruptcy, which MAY wipe out all subsequent liens against you.
In all cases, I would suggest you sit with an attorney to understand the options and how they affect you long term.
It sounds like your ex-husband is not understanding how those options will affect him as well. If I were you, I might offer to pay his consulting fee to have someone explain his options to him. I would think that he would want to select an option that would be least detrimental to himself financially, no matter what his feelings are for you. But he may need to obtain this information without feeling you are influencing the decision he would make.
Might that be the case? You can always have him read the blogs here on Trulia! :)