"She had a light that words can't capture but touched everyone she came into contact with", Brosnahan wrote on Instagram alongside a video of the designer dancing with Andy Spade.
He said she "sounded happy" the night before her death, and added that his priority is caring for their daughter as she deals with her "unimaginable grief".
Reports that Cariaga and Spade were close friends has at least some evidence to back it up.
Frances Valentine, with which she was involved until her death, focuses exclusively on shoes and handbags. Not surprisingly, the shoe that originally retailed for around $400 is sold out everywhere. She said she never had any regrets about selling Kate Spade New York and shared a humorous story about going into a Kate Spade store to purchase her daughter a gift.
Spade's sister Reta Saffo said the fashion icon had suffered from years of depression and had refused to get treatment.
Police have previously said that she left a note pointing to "a tragic suicide", but her husband, Andy Spade, said on Wednesday that he had "yet to see any note". This is not your fault.More news: Val Kilmer Will Rejoin Tom Cruise in 'Top Gun' Sequel
"I'm sad for [Spade's] daughter, for that to be in the note because my husband left a note", she continued. I beat cancer! Let's celebrate!
She was proud of the table she set at Spade's Napa Valley home in August of 2017.
As the media coverage of Kate Spade's apparent suicide is showing no signs of subsiding, one of the designer's brothers, Earl Brosnahan, issued a statement Thursday thanking the torrent of strength people have provided and took aim at erroneous leaks to the media.
Kate, his wife of 24 years and longtime business partner, died by suicide Tuesday by hanging herself in a bedroom in her apartment. In a statement written to the New York Times, Andy said that his wife was the "most beautiful" and the "kindest" person he has ever known.
Reuters Kate Spade arrives at the Council of Fashion Designers of America awards in New York on June 2, 2003, at the New York Public Library.
"Kate was the most handsome woman in the world", he shares with E! They named their second organization after their 13-year-old daughter. The pair had amicably separated about 10 months before her death. She loves spending her time outdoors as much as possible. "We would ask that our privacy be respected as we grieve during this very hard time".