Legal Question in Real Estate Law in California

I would start by taking her back to the family law court on a contempt OSC, and ask the judge to re-allocate the proceeds of the sale to account for her failure to do what she was ordered to do.

Can you sue? Yes, absolutely. Will you win? That's another matter. Here's my analysis.

Since you say "ordered to be sold," I assume this was part of the court's decree and not a private contract (marital settlement agreement). I think the failure to comply would then be a tort matter (breach of a duty imposed by law) rather than falling under contract law (breach of contract) but the result may be the same. Watch out, however, for a difference in the statutes of limitations. The tort deadline seems to be fast approaching.

It will be fairly easy for you and your lawyer to prove a duty and a breach of the duty, and a loss, at least a loss on paper. There remain two other factors to be established to make your case: causation in fact and proximate or legal causation. The first can probably be shown by expert testimony on changes in market value, turnover rates, and so forth. It can probably be shown that "but for" your x's delay, the loss would not have occurred.

However, the establishment of legal or proximate cause is more difficult. Even the concept of proximate cause is difficult to explain. It's sort of like this: did your x's breach of her duty to sell promptly CAUSE your loss? The answer probably is no, the loss was caused by a "superseding cause," a decline in the market. This principle is discussed at some length in a case called Safeco Ins. Co. v. J & D Painting (1993) 17 Cal.App.4th 1199, at pages 1202 to 1205.

A full analysis of the facts and further research into case law might reveal ways to win this case despite the "superseding cause breaks the chain of proximate cause" defense.