Cheating, nude parties and more

Domestic diva Martha Stewart is “blatantly lying” when she claims her ex-husband, longtime New York publisher Andrew Stewart, was unaware that she was cheating on him during their tumultuous 30-year marriage, a source exclusively tells The Post explained.

“Andy was certainly aware of all of Martha’s affairs and pseudo-affairs and her many flirtations from day one,” a close confidant of Andy’s told me. “He knew about all the men who were in and out of her life, whether real or in her imagination. But there was no secret lover, as Martha claims. Andy knew everything Martha was up to, was aware of every guy.”

According to the insider, “Andy is just really pissed” that Martha is using him and their failed marriage – which ended more than three decades ago – to promote “Martha,” the much-hyped Netflix documentary about her life, which airs Wednesday becomes.

While promoting the film, 83-year-old Martha admitted to cheating on Andy during their marriage. She boasts that it was “very easy” to keep her alleged affair a secret from him for about three decades and advises viewers: “You have to be prudent” – that is, be careful and not be willing to take risks.

As the author of Just Desserts, the New York Times bestseller about Martha, I revealed that she was indeed a risk-taker when it came to indiscretions outside of her marriage.

Among other things, sources told me how Martha once eloped for the night with a handsome stranger she and Andy met on their honeymoon in England, leaving her groom shocked and forced to sleep alone. She later allegedly hosted swinger-style pool parties, where she flirted with and groomed male guests, at the Turkey Hill estate in Westport, Connecticut, made famous by her Martha Stewart Living magazine and TV shows.

“Men chasing Martha, or their involvement, real or imagined, was never a secret to Andy or the couple's close friends at the time,” the insider claimed. “Martha will do everything she can to stay in the public eye and be known publicly as she gets older. She even publicly brags about cheating on her husband. It's all very bizarre. Only a woman with little to no morals and no respect for the sanctity of marriage would brag like that just to hype up a movie about her and get media attention.”

The Stewarts married in 1961 and had a daughter, Alexis, five years later. But the marriage fell apart as Martha's fame and independence grew. The Stewarts separated in 1987 and their acrimonious divorce was finalized in 1990.

Andy, now in his eighties, later married Martha's assistant Robin Fairclough, but this union also ended in divorce. He is now married for the third time, while Martha remains single.

According to sources, Martha allegedly denigrated him in front of others, calling him “boring, disgusting, silly” and treating him more like a reviled servant than the husband many believed to be the mastermind behind Martha's early publishing successes.

During one of the verbal altercations described in my book, Martha claimed that she had slept with another man during a business trip to Los Angeles. Andy was shocked, but Martha dismissed the alleged rendezvous as “a one-time thing… unimportant… uninteresting… just an experiment.”

But others close to the Stewarts also knew at the time, such as the writer Jonathan Fast, the third husband of the writer Erica Jong, that Martha was playing around – sometimes in the hot tub outside Fast's bedroom.

“People were cavorting naked,” a male friend of Martha’s recalled of these gatherings. The same type of perverted activity occurred at the Stewarts' home.

Recalling one occasion at Turkey Hill, Fast said, “Martha spent the entire evening flirting with a very handsome and very successful married banker. The flirtation was extremely blatant and aggressive. I felt left out because Martha wouldn't flirt with me. She was very good-looking, but she just always seemed very cold and manipulative and cutthroat.”

Erica, he added, “thought Martha was a slut.”

While Martha recently bragged about keeping an affair secret from Andy for “30 years,” Erica Jong, a classmate of Martha's at Barnard College, disagreed.

“I always heard that she was involved with people and had a lot of affairs,” Jong claimed.

The Post has reached out to Martha's rep for comment.

During her rise to the top, Martha worked for a time as a stockbroker, using her feminine charms and her “big legs,” as one associate recalled, to drum up deals. One person who chose her was married stockbroker and work colleague Brian Dennehy, who later became a popular actor.

The two became close and had what Dennehy called a “strong mutual attraction”; He also told me that he couldn't take his eyes off her. “Back then she was thin and beautiful and extremely sexy,” Dennehy said.

While Dennehy claimed they never had an affair, he admitted: “I would dream of being with her.”

Andy allegedly suspected that his wife's boss, Andy Monness of Monness, Williams & Sidel, also had a thing for Martha. Monness denied any kind of affair and raved about her: “Martha was my dream woman. She had the magic.”

At some point, Andy supposedly had enough of her teasing and flirting and supposedly had to face one of Martha's more zealous pursuers, millionaire Andrew J. Stein, who once unsuccessfully ran for mayor of New York. Stein told me he sent her flowers and invited her for a drink at Raffles, a romantic private club in the Sherry-Netherland Hotel.

Stein called it “playful flirting,” and Martha was flattered by the attention. He thought she “had great looks and that her reaction to me was quite friendly.”

But angry Andy had finally done it. When Stein went too far with his calls to Martha, he told meAndy finally got on the phone and warned, “Keep that shit away from my wife!”

And Stein did.

Later, as a divorcee looking for Mr. Right, Martha took after her old stockbroker friend Dennehy, who was now a successful actor, and was apparently hoping for a relationship.

“I felt like she had a fantasy of meeting him and showing Andy that she was still viable,” Stewart's old friend Kathy Tatlock told me. “She said she always thought Dennehy was a very attractive guy.”

Martha met him by chance in New York. He found her even “livelier” than ever and took her to a premiere and an afterparty.

“Having her in your arms isn’t so bad,” Dennehy remembers.

But it was never more than that.

Why?

Dennehy told me, “Martha is one of those women who intimidates the hell out of men.”