Kate Spade, the world-renowned fashion designer who was found dead of an apparent suicide, long suffered from depression and anxiety and had been under treatment for five years, her husband and business partner said Wednesday.

"She was actively seeking help and working closely with her doctors to treat her disease, one that takes far too many lives. We were in touch with her the night before and she sounded happy," Andy Spade said in a statement.

"There was no indication and no warning that she would do this. It was a complete shock. And it clearly wasn't her. There were personal demons she was battling," he said.

Andy Spade acknowledged that he and his wife had been living apart for the last 10 months, maintaining different apartments a few blocks from each other in Manhattan. He said the couple was not legally separated and "never even discussed divorce."

"We ate many meals together as a family and continued to vacation together as a family. Our daughter was our priority. ... We were best friends trying to work through our problems in the best way we knew how," he said.

Spade, 55, was found dead in her New York City apartment on Tuesday.

On Thursday, the New York City Medical Examiner's Office announced that her death was a suicide by hanging.

Spade's older sister, Reta Saffo, said that the fashion icon's suicide was "not unexpected" and that her sister had struggled with mental illness.

In an email to NBC News, Saffo has said that her younger sister was a "precious, precious little person" and "genuine in almost every way" but that her fame exacerbated what she believed was a bipolar disorder.

"She was surrounded by 'yes' people, for far too long, therefore she did not receive the proper care for what I believed to be (and tried numerous times to get her help for) bipolar disorder ... stemming from her immense celebrity," Saffo said.

Earlier Wednesday, a source close to the family disputed Saffo's account, describing Spade as a "kind, generous, funny, warm and extremely private person."

In a statement, the source said: "The family is disgusted and saddened that at this time of great sorrow, Kate's sister, who has been estranged from the entire family for more than 10 years, would choose to surface with unsubstantiated comment. Her statements paint a picture of someone who did not know her at all."

In an earlier email to The Kansas City Star, Saffo, who lives in Santa Fe, New Mexico, said she had frequently flown out to Napa, California, and New York over the last four years to get Spade treatment.

However, when Spade was all set to go, she "chickened out by morning," Saffo said.

Saffo said Spade feared that hospitalization would hurt her brand and tried to self-medicate with alcohol.

"I even said I would go with her and be a 'patient' too (she liked that idea). I said we could talk about it all — our childhood, etc. That I could help her fill in any blanks she might have," Saffo told The Star. "That seemed to make her more comfortable, and we'd get sooo close to packing her bags, but in the end, the 'image' of her brand (happy-go-lucky Kate Spade) was more important for her to keep up. She was definitely worried about what people would say if they found out."

Other members of Spade's family did not corroborate Saffo's description of her sister.

Spade's brother-in-law, the actor David Spade, commented only on social media after her death on Tuesday. David Spade is Andy Spade's brother.

"I still can't believe it," he wrote in a post on Instagram. "It's a rough world out there people, try to hang on."

He remembered her as "so sharp and quick on her feet" and said, "She could make me laugh so hard."

In a 2017 interview with NPR, Kate Spade said she suffered from anxiety and often felt like "the sky is falling."

Saffo said her sister asked her to attend her funeral. "One of the last things she said to me was, 'Reta, I know you hate funerals and don't attend them, but for me would you please come to mine, at least. Please!' I know she perhaps had a plan, but she insisted she did not."

Saffo said it's possible her sister's decision to die by suicide began when news broke of Robin Williams' suicide in 2014.

Spade was fixated on the coverage of the actor's death, according to Saffo, and watched the news coverage from a hotel in Santa Fe.

"We were freaked out/saddened," Saffo said. "But she kept watching it and watching it over and over. I think the plan was already in motion even as far back as then."

If you or someone you know is in crisis, call the National Suicide Prevention Lifeline at 800-273-8255, text TALK to 741741 or visit SpeakingOfSuicide.com/resources for additional resources.