Iv never heard her slip up. I don't think there's any big family secret. I think she's just the black sheep of the family. They find her mental health shameful, she isn't invited to family events because she can't control her drinking, the stuff she's accused her uncle of, nobody comes round anymore because the house is a biohazard and it's not worth the accusations and drama. I think she swears on her nieces life as a way of romanticising her life. Pretending these people are actually present to her.