I don't see what the fact that your daughter in law is from Eastern Europe and, according to you, doesn't have citizenship has got to do with anything. If you project that sort of attitude perhaps that is one of the reasons the relationship has gone wrong.
You say you told your son that you were moving away and he said nothing. Given the amount of animosity, what did you expect him to say? Are you going to move or was it just a threat? Why is your daughter in law "terrified" to bump into you?
Perhaps your son's wife is controlling, or perhaps there's a battle for control from both parties. It's difficult for anyone to know on the information available.
Grandson of New Limerick (Son of New Limerick contd.)
What’s a household item that reminds you of your grandma’s house?
After 10 years of estrangement I was invited into my son's house.
