The Duchess of York broke down in tears as she recalled how her late mum Susan Barrantes would slap her, as part of an emotional therapy session filmed for her upcoming TV show Finding Sarah.
In the six-part documentary series, she admits she was just a toddler when Barrantes spotted a vein on Ferguson's face that she called the "sign of the devil", which she tried to beat out of her.
Wiping away tears on camera, Ferguson recalls, "When she used to hit me because I didn't sit on my potty or wouldn't eat, a little vein would come up on the centre of my head near my red hair... It's just the way I was brought up. No wonder I'm so flawed."
Ferguson goes on to reveal she blames herself for the breakdown of her parents' marriage, after Barrantes ran away with an Argentinian polo player.
She adds: "I believed I caused my mother to leave and therefore I am worthless and unlovable."