"She was a prisoner," Kesha's mother, Rosemary Patricia "Pebe" Sebert tells Billboard in an exclusive interview out today.

"It was like someone who beats you every day and hangs you from a chain and then comes in and gives you a piece of bread. Luke would say, 'You look nice today,' " says Pebe, "and send her into hysterics of happiness because she was programmed to expect nothing but abuse."

The bombshell, in-depth exclusive details the saga of Kesha, Dr. Luke and a mother's fight: "he almost destroyed us," she explains.

Read the full piece here.