Sinead O'Connor is opening up about the horrifying sexual abuse she suffered at the hands of her mother in an emotional interview on Dr. Phil. The Nothing Compares 2 U" singer ... detailed how her mother Marie O'Connor "ran a torture chamber" and tormented her until she ran away from home at 13. "She was not well. She was very, very, very not well. I would say she was possessed. Although I'm not sure I believe in such things," O'Connor, 50, said."I ran away," the singer added. "She used to make me say over and over 'I am nothing. I am nothing' or else she'd beat me." Marie O'Connor died decades ago in a car crash when Sinead was 19 years old. O'Connor has made headlines in recent years for her erratic behavior. Despite this, she denied that she is mentally unstable, telling Dr. Phil, "I am fed up of being defined as the crazy person; the child abuse survivor."