Walt Disney and Mickey Mouse statue at Disneyland Orlando. Still frame for contextual reference only.
Perhaps the biggest determining factor in somebody cutting a toxic relative out of their life is when kids end up being involved. Behaving badly towards an adult is one thing, but lashing out at defenseless children is often where people will draw the line. Most of all, it is important to make sure that unhealthy patterns do not have the chance to repeat.
A mom was left feeling like it was time to stop speaking to her mother-in-law after she ruined a family vacation. She had offered to cover part of the cost if she and her husband let her join on the holiday with their two kids, but the money saved didn't seem to be worth it. The MIL constantly talked down to her son and granddaughter, and behaved unacceptably towards other people.
The parents agreed that things couldn't continue like this, but they also knew that their children wouldn't receive an inheritance from their grandmother if they ceased all contact. It left them with a dilemma that felt hard to solve.