Kesha's mother, Rosemary Patricia "Pebe" Sebert, is speaking out about the abuse she says her daughter suffered at the hands of music producer Dr. Luke. In a new interview with Billboard, Sebert claims that the pop star was a "prisoner." "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," Sebert says of Kesha's relationship with Dr. Luke (real name Lukasz Gottwald). "Luke would say, 'You look nice today' and send her into hysterics of happiness because she was programmed to expect nothing but abuse." Sebert, a songwriter based in Nashville, added that her daughter's contract with Sony currently keeps her career under the producer's control. He has to approve any other producers she chooses to work with and has "final say," Sebert tells the magazine. Sebert also reveals that Taylor Swift's donation of $250,000 to the singer's cause was initially considered suspect. "It was really random," says Sebert. "Kesha was like, 'Are you sure it's not some scammer?' And then she said, 'I would be honoured if she wants to do that.'" The full interview is available here.