phil-I am so sorry that your son and your family are going thru this difficult and scary time. It was good to learn the doctors got the tumor out, hopefully your son will respond to the other treatments the doctors are likely to give.
It is even more horrible that his in-laws are trying to blackmail your son into never seeing you. It is good that his wife is refusing to go along with her disillusioned, demented parents.
I wish you and your son and your family the very best of outcomes!
PTN