I’d love to hear your parents side of the story. They were deeply hurt by their parents. Possibly your setting boundaries was perceived by them as a betrayal.

Your mother’s prediction about your children one day losing interest indicates that she has been programmed to expect rejection. Both your parents learned early on that people you love hurt you. This is the child/parent relationship that is familiar to them. Their distancing themselves is a defense mechanism.

Keep being compassionate, even when they bleed on you from cuts someone else made. The elderly are in a vulnerable place, but they are also in a position to reassess and change their perspective. See if you can get them to talk and then just listen. Maybe that will help.