Kathy Hilton won't return for RHOBH season 13, focusing on daughter's reality show.
Sister Kyle Richards reveals strained relationship with Hilton post-season 12 reunion.
Hilton joined as a "Friend of" the franchise in season 11, became a fan favorite.
Second season marred by off-screen meltdown allegations and conflicts with cast members.
Lisa Rinna, who witnessed Hilton's behavior, announces her departure from the series.
Hilton expresses dissatisfaction with Rinna and Erika Girardi, accuses them of bullying.
Hilton demands changes in the cast and won't return if it remains the same.
Rinna and Girardi accused of leaking information about Hilton's meltdown.