Kate Spade’s best friend, Elyce Arons, sells memoir about their relationship to Simon & Schuster

Kate Spade’s best friend is writing a memoir about her relationship with the tragic designer, Page Six hears.

Sources say that Simon & Schuster’s Gallery Books has snapped up the tome by Elyce Arons, which chronicles their decades-long friendship and business partnerships.

Arons helped to found both the Kate Spade label and Spade’s final project, Frances Valentine, with her pal.

The book, titled “We Might Just Make it After All,” tells the story of their meeting in college in Kansas in 1981 — where they bonded over their love of the “Mary Tyler Moore Show” — and their goal of coming to New York to make it big.

Arons and “Katy,” as Elyce called her, “lived out their wildest dreams and madcap adventures not realizing their brand would reach iconic status,” according to a source close to the book.

We hear Hollywood is already circling the project.

Sources say that Arons’ book ends before Spade’s 2018 suicide.

(We’re also told that it’s not creating any friction behind-the-scenes as insiders — including Spade’s widower, Andy — are comfortable with the project).

Spade left Kate Spade in 2007 after Liz Claiborne bought the company. In 2016, after Spade waited out a non-compete period, she and Arons launched Frances Valentine.

Arons remains the CEO of that brand.