Cynthia Some mother-in-laws have no cure. They are just built to hate. Its in the fabric of their existence. A mother-in-law who loves her son (or daughter) should learn to accommodate and respect her child’s decision.
It is okay to warn and advise your child about impending danger but then, there are other ways to drive your point instead of fighting tooth and nail to destroy something that is created out of love (or otherwise) between two people.
Worse is that many educated adults are even far more guilty of this than the illiterate mother in laws