What is my legal right/entitlement during divorce proceedings?

We were purchased a car (for me) with the intent of taking out a second mortgage to pay cash for it. Mother-in-law purchased the car for us with "the same terms" to be paid off when house sells. We ended up taking a loss on the house and didn't pay off mother-in-law. Now ex-wife wants me to pay off the car in full even though it was a community debt; I am expected to assume the entirety of that debt. What am I entitled to in this case?