J. WHO? Courtney Crangi Revealed as Jenna Lyons' Mistress!

J. Crew president and creative director Jenna Lyons has been making news as of late because of her messy divorce from husband Vincent Mazeau, who's seeking a HUGE settlement, with whom she shares a son, and who she allegedly left for a woman.

Courtney Crangi has been identified as that woman.

Here's Jenna Lyons (left) and her new girlfriend ...

The fashionable pair heretofore known as Jourtney. On THG at least.

Courtney Crangi also works in the fashion industry, the NY Post reports, presiding over the business side of her brother Phillip Crangi's high-end jewelry line.

An insider tells Page Six that it was over between Lyons and Vincent Mazeau before their involvement: "After the breakup, Jenna fell in love with Courtney."

"The two had been close friends for some time."

"She and Courntey known each other for years through the fashion business. Courtney is an attractive blonde who balances working hard with her family."

Reportedly Jenna and Courtney have been seen out and about together in NY City's West Village and are quietly open about their new relationship.