The eponymous designer was found hanging by a scarf in her New York City home. The New York Times reports that Spade left a note for her 13-year-old daughter, saying that what happened was not the teen's fault. Spade was 55 years old.
RELATED: Designer Kate Spade found dead in apparent suicide
Spade's handbag line is loved by a generation of American women who grew up in the 90's alongside Spade's brand, which evolved into a fashion and lifestyle empire.
But according to her sister, Spade's health did not match her sunny style.
RELATED: Kate Spade's Sam bag: A look at her iconic handbag
Reta Saffo told the Kansas City Star the past three or four years, Spade suffered from debilitating mental illness and that her suicide was "not unexpected". Saffo told the paper she frequently visited her sister in New York and Napa, where Spade had a vacation home.
She was trying to convince her sister to seek treatment.
RELATED: After Kate Spade's death, fans share what storied designer's work meant to them
When Robin Williams committed suicide in 2014, Saffo said Spade was interested in the news, saying "she kept watching it and watching it over and over. I think the plan was already in motion even as far back as then."
After multiple attempts to help her sister Saffo said she finally "let go," adding, "sometimes you simply cannot SAVE people from themselves!"
National Suicide Prevention Lifeline
We can all help prevent suicide. The Lifeline provides 24/7, free and confidential support for people in distress, prevention and crisis resources for you or your loved ones, and best practices for professionals.