To look at it from her point of view - she gets a van that, if well maintained, may last another 4-5 years, and she gets to raise the children by herself the majority of the time. She does not get to spend the child support however she wants - she has to support the kids with it. She will have to find a place to live, a job AND a reliable babysitter, which is not easy, and she will have to pay the babysitter an enormous chunk of the proceeds from her work. Oh, and she also gets to pay for insurance on the van you are "giving" her, rent (not cheap, either), food, clothing, school supplies and fees, etc.
It sounds to me like you won't be able to afford to keep the house after the divorce, anyway. Walking away without the debt may be the best thing for you.

