Women can be so f@cking evil it's untrue
I'd have her brought up on charges for selling a vehicle that doesn't belong to her. His name was on the V5 so she had no legal right to sell it. Go to the police and go mad. They will try and fob him off saying there is nothing that they can do. There is plenty they can do it's just a case of them getting off their backsides to do it.
Gotto feel sorry for the kids though in this sort of thing as it's they who tend to suffer the most. Saddly I speak through experience