On the show at a New York competition, Abby got into a verbal altercation that turned physical with Kelly Hyland, the mother of two of her dancers -- Paige and Brooke Hyland. The situation ...

That's why the Dance Moms alum didn't join former costars JoJo Siwa, Brooke Hyland, Paige Hyland, Kalani Hilliker, Kendall Vertes and Chloé Lukasiak in the new Lifetime documentary special.