More than two decades after their split, ANJELICA HUSTON is STILL in love with JACK NICHOLSON!

In a stunning new memoir, the Oscar-winning actress will admit that she never got over their breakup.

And she will not only rip the lid off the intimate details of her wild life with Jack, she’ll also detail publicly for the first time what really happened the night director Roman Polanski raped a 13-year-old girl in Nicholson’s Hollywood home in 1977.

"Breaking up with Jack was more brutal for Anjelica than the death of any relative or friend," a publishing insider familiar with the book proposal told The ENQUIRER.

"Losing him devastated her and she never really recovered."

A sought-after model in the 1960s, Anjelica, now 59, became a regular on the Hollywood party scene. In 1973, she moved in with Jack Nicholson, who’d gotten his big break in "Easy Rider" just a few years earlier.

"Their life together was Hollywood at its most hedonistic – and drugs were a big part of it," said the source, who added that Anjelica has signed a deal with publisher Scribner Books to release the memoir in 2013.

In 1977, Anjelica found herself at the center of one of Hollywood’s biggest scandals when good friend Roman Polanski, then 43, arrived at Jack’s Mulholland Drive house with 13-year-old Samantha Geimer.

He allegedly plied the young girl with champagne and drugs before having sex with her.

"Anjelica was there," the source said.

 "She knows ALL the details and plans to reveal them in the book."

Anjelica – daughter of legendary director John Huston – was arrested the next day for cocaine possession, but charges were later dropped when she agreed to give evidence against Polanski. However, Polanski fled the country and was never brought to trial.

Anjelica moved out of Jack’s home in 1985, but continued to date him until 1989, when she learned he’d impregnated actress Rebecca Broussard.

"Happiness eluded her. What she wanted most was to marry Jack and have a baby," said the source.

Anjelica went on to wed sculptor Robert Graham in 1992, but the couple never had children. He died in 2008.

"Anjelica’s lived an amazing life," the source said. "And when her story finally comes out, Hollywood will be buzzing for years!"