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Nicole Kidman’s worst nightmare is being revisited as her split with country king Keith Urban has dredged up memories of the details of his addiction demons laid out by former pal and songwriting partner Vernon Rust.

The Hours Oscar winner, 58, filed for divorce late last month, citing irreconcilable differences, after futilely fighting to save the pair’s rocky romance, sources say.

The move marks a dramatic change from their initial months as husband and wife in 2006 when Nicole lovingly staged an intervention to help the struggling performer, who’d relapsed by going on a boozy bender while on tour, and stayed in the relationship as he checked into the Betty Ford Center in California to receive treatment for substance abuse.

At the time, Urban released a statement that read: “I deeply regret the hurt this has caused Nicole and the ones who love and support me. One can never let one’s guard down on recovery, and I’m afraid that I have,” per Daily Mail.

The “Blue Ain’t Your Color” singer’s Betty Ford stint was his third trip to rehab, having previously sought help in 1998 and 2000 after wrestling with a dependence on alcohol and cocaine.

Vernon — Keith’s collaborator from decades ago during the hitmaker’s tenure with the band the Ranch — dishes about his old pal in his shocking memoir, Fake News.

The tunesmith, who himself spent 14 years hooked on crack, claims in his book that he and Keith once snorted $320,000 worth of cocaine in the late 1990s during an “epic” multi-day binge.

“We lived in the studio. We did a lot of coke, and stayed up for days,” Vernon shares.

He also claims that Keith used “coke, crack and weed.”

But even before Vernon’s book bombshell dropped, Keith’s loose-lipped former bestie — who some have called Urban’s fixer — was telling all about the artist’s rock-bottom days as an addict.

Vernon met Keith in Nashville, Tenn., in 1993, and the men began writing songs together.

“We became friends, then best friends, then we became freakishly inseparable. We spent all our hours together,” Vernon recalled.

But while working with the Ranch on the band’s self-titled 1997 album, Vernon said drugs were “just there.” He explained, “We all got into it. Keith more than anyone.”

Vernon added: “Keith’s thing was crack, and lots of it. He was the big rock star, so he always got the first pick of the drugs when they turned up.

“He’d take a rock for a hit, then take more and hide them in his pocket or somewhere.”

“He’d go off on benders, and someone would find him in a crack den curled up in the fetal position.”

“He’d take the hit and crawl under beds, crawl across roofs, walk off and vanish — not come up for days.”

Now 58, Keith, who shares daughters Sunday Rose, 17, and Faith, 14, with Nicole, has openly discussed his difficult past. In 2015, the Enquirer reported that he confessed, “I was going to lose it all. It was like, ‘If I don’t choose this moment to do the right thing and do something that’s going to give me life, all of the things I’m scared of losing, I’m going to lose anyway.’”

But as Keith found his way to sobriety and superstardom — which led to him serving on the judging panel of American Idol and Australia’s version of The Voice — Vernon watched his former buddy’s success from afar.

“Keith was everywhere. The newspaper in Nashville featured him all the time. He was on American Idol, he had married Nicole,” he recalled. “If I had told him years earlier he would be on American Idol, I swear he would have hit me and told me to take it back, ‘That’s as low as you go!’”

When asked how he’d react if he saw Keith again — after all they had been through — teary-eyed Vernon said: “Yes, he can be a hard-nosed, ball-assed son of a b**ch. Yes, he ruined me. Yes, he’s become a bit too obsessed with his hair.”

“But, man, I tell you we would still hug like brothers and there would still be magic there if we sat down and wrote a song.”