DH’s mum is a controlling narcissist who gave him and his brother an unhappy childhood and a lifetime of mental and emotional difficulties as a result. Part of her MO was to keep them treading on eggshells, always wondering where the next spiteful sideswipe or inexplicable overreaction would come from.
When they moved away and became independent adults with partners, she couldn’t bend them to her will anymore, so instead would just drop little toxic bombs to keep everyone on their toes.
One of her specialties was to save some really nasty/critical remark to the end of a visit - always delivered in a breezy, butter-wouldn’t-melt tone, as though she had no idea how hurtful her words were. She absolutely did, but always gave herself plausible deniability.
Ruined every single visit, no matter how well we thought it had been going, no matter how hard we’d worked to host them, or how much effort we’d made to go and see them. It was her way of dropping a little turd on the whole thing - to what end I have absolutely no clue.
Sorry your mum is equally horrible, OP. It sucks.