It's very sad for everyone involved. As far as the laws go here the stepson was probably legally entitled to at least 75% of the cars and house.
If the wife had a will, she could have given her foreigner husband the usufructuary right to those properties.
There is probably a lot more to this story. It seems to have escalated pretty quickly.
If you and your wife/girl friend don't have a will you might want to think about getting one written up. It can save a lot of hassles and misunderstandings. Having a usufructuary right can give you a lot of privileges you wouldn't normally get.