What a horrible situation for you and your children to be in.  I would hate to think that you have no recourse at all but it is difficult to asses without reading your divorce papers and what was written in them as to the asset, its distribution, etc.  At the very least he stole the money if the asset is deemed to be that of the children's.  You need to go and seek legal help in your area as to what to do as soon as you can.  Ask about requesting an injunction as to anything regarding the house.  Meaning he can not transfer it or encumber it anymore than it is with loans before the litigation is decided.  And the kids may be the ones to be the plaintiffs.  Explain to them that they will be suing their Dad.  Not the best position to place them in but you may have no choice.  Good luck.