Even if the car is sold and she gets some money for it, then it is still only a short term solution. Once the money is spent then she'll be looking for other ways to get money from him.
If she's living in a house that's too expensive for her to run now that there's only her income covering the outgoings then she needs to consider either moving to somewhere more affordable, reducing her outgoings or finding a further source of income.
I'd recommend her having a word with the solicitor who dealt with the divorce for advice as to whether he can be persuaded to provide some money to help with raising the children if she is strugging as much as you say she is.
Wedding and Party DJ. Resident DJ at the Coach and Horses, Chapeltown. Public Liability Insurance £10M.