A note was found on a bed near Spade's body that was addressed to her 13-year-old daughter, Frances Beatrix Spade, TMZ reported.
The 55-year-old says his wife and longtime collaborator had suffered from depression and anxiety for a number of years, and was "actively seeking" help from doctors and taking medication for her illnesses.
The 55-year-old designer was found by her housekeeper in her Park Avenue apartment Tuesday morning, after apparently hanging herself.
USA media reports claim Spade and husband Andy had split in the months leading up to her death, while TMZ claim he had moved out of the family home.
"She was definitely anxious about what people would say if they found out", Saffo tells the newspaper via email.
Over the years, Brosnahan and Spade appeared together on red carpets and other events as the actress' star rose. "We loved each other very much and simply needed a break", he said in his statement.
In a suicide note left for the couple's daughter, Spade reassured the teenager her death wasn't her fault.
They had continued to co-parent their daughter during this period, and saw one another or spoke "every day".
Anna Wintour, the grand priestess of fashion and editor-in-chief of Vogue magazine, hailed Spade as a woman who "defined" authenticity. They launched Kate Spade New York in 1993 and sold the last of their shares in 2007. Spade's sister, however, told the Kansas City Star she'd "come so VERY close to getting her to go in for treatment".
While many remember Kate Spade for her fashion empire, the designer hoped it wouldn't be her only lasting legacy. "This was someone that really valued her private life and I don't think Kate could live in the cruel world that we live in today".
In the 25 years since Kate Spade's founding of her handbag line, the name has become a byword for a certain preppy style.
"Kate was the most attractive woman in the world".
"Her statements paint a picture of someone who didn't know her at all", the source adds. Her company, Kate Spade New York, has more than 140 retail shops and outlet stores across the country, as well as more than 175 stores internationally.