Kate Spade's husband reportedly asked for a divorce before she was found dead.

The 55-year-old fashion designer tragically died in her apartment in New York City earlier this week in an apparent suicide and, although the reason for her ending her life still remains a mystery, police have reportedly learnt that her spouse Andy Spade - the brother of actor David Spade - had left her and was living in a nearby flat.

A source told TMZ that Andy, whom she was married to from 1994 until her death, had requested a divorce but the handbag designer didn't want to end their marriage.

It's believed Kate left a suicide note when she died and in the heartbreaking letter she told her 13-year-old daughter Frances Beatrix, whom she has with Andy, that she has ''always loved'' her and that she shouldn't blame herself for what she's decided to do.

Meanwhile, Kate's sister Reto Saffo has admitted her suicide didn't come as a shock to her because she's been battling with severe depression for years.

She said recently: ''I will say this was not unexpected by me. She was always a very excitable little girl and I felt all the stress/pressure of her brand (KS) may have flipped the switch where she eventually became full-on manic depressive. I'd come so VERY close to getting her to go in for treatment (to the same place Catherine Zeta-Jones went for her successful bipolar treatment program). I'd spoken with them on the phone (not telling them exactly who the patient would be). They agreed to fly in and talk with her and take her with them to the treatment centre.

''She was all set to go -- but then chickened out by morning. I even said I (would) go with her and be a 'patient' too (she liked that idea) . . . 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.''

Kate was a successful designer, having founded Kate Spade New York in 1993.

The line began by designing its famously colourful handbags before expanding into other accessories and clothing, and eventually became a billion dollar brand.

Kate sold her ownership stake in the brand in 2006, and in 2016 she revealed she had taken time away from designing in order to focus on motherhood.