Kesha's former manager, David Sonenberg, browbeat her to do whatever it took to lose weight, including doing drugs, vomiting and starving herself.
"One time on a conference call, Sonenberg was screaming, 'You need to lose weight! I don't care what you do — take drugs, not eat, stick your finger down your throat!" Kesha's mom, Pebe Sebert, told People.
"Ke$ha was just weeping. She drove around afterward thinking about killing herself."
Kesha, 26, checked into rehab to treat her anorexia and bulimia on Jan. 3. Kesha told Sebert she had been anorexic and bulimic since age 18 (when she signed with her former manager), and had been repeatedly fat-shamed by Sonenberg.
Sebert said Ke$ha's longtime music producer, Lukasz "Dr. Luke" Gottwald, joined in on the fat-shaming.
"He has just always been very disrespectful about her weight," said Sebert. "He'd say it in certain ways, like 'Why don't you try running?' She was doing everything and not getting thin fast enough, and that's when she first became bulimic."
Both Dr. Luke and Sonenberg have denied the weight-bullying accusations. Sebert, who recently joined Ke$ha in rehab for post-traumatic stress, said her daughter almost died from anorexia and bulimia-induced starvation.
"I've watched my beautiful, self-confident, brilliant daughter be berated and ridiculed for her looks and weight to the point that she almost died," said Sebert.
"The doctors told me her blood pressure and sodium levels were so low, they'd never seen it that low except with someone who'd had a heart attack or stroke. They said it was a miracle she hadn't already dropped dead on stage."
Sebert said Kesha tried to hide her bulimia and claimed her dramatic weight loss was due to diet and exercise. "She could throw up really quickly and quietly," said Sebert. "She'd even take a bag in there so no one could see her bent over the toilet. She was really sneaky."
Ke$ha is being treated at Timberline Knolls, outside of Chicago. It's the same clinic where Demi Lovato was treated for anorexia and bulimia. Lovato detailed her recovery in her book Staying Strong: 365 Days a Year.
Sebert said Kesha eventually wants to use her bulimia battle as a platform to raise awareness of the dangers of eating disorders. For now, Kesha's top priority is her health.
"At this point, she doesn't care if she ever makes a record again," said Sebert. "She just wants to be healthy and happy."