OP here... thanks for the comments! My fiancé did essentially tell her to shove it. She did apologize (after missing his masters graduation), and he still hasn’t quite forgiven her. As for what this means for the future... luckily, my fiancé is NOT a mamas boy in the least, and is happy seeing her once or twice a year. He, my mother, and I have a bet going on what sets her off next. Personally, my money is on the day she realizes we aren’t giving her grandkids.