I have asked the same question myself. It becomes part of their identity and nothing you do can change it. Nothing you could have done to change it as she would just keep moving the goal posts. This often is accompanied by alcoholism/addiction

No matter who climbs in her sandbox, it’s always how she plays and if you don’t play her way you get scolded and kicked out.

This is how my older sister was and still is. She needs to have the control and part of her MO is having a victim mentality that is very twisted, controlling and entitled.

Therapists told me the same thing that I was dealing with a disordered person either BPD or NPD.

The best thing to do is mentally divorce yourself because this is not anything you can change.