Cheating, naked parties & more

Domesticity diva Martha Stewart is “blatantly lying” when she claims her ex-husband, longtime New York publisher Andrew Stewart, was unaware that she had cheated on him during their turbulent 30-year marriage, a source exclusively told The Post.

“Andy certainly was well aware of any and 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 of all the men who were in and out of her life, real or fantasized. But there was no secret lover, as Martha maintains. Andy knew everything Martha was up to, was aware of every guy.”

According to the insider, “Andy’s just very pissed off” that Martha’s using him and their failed marriage — which ended more than three decades ago — to promote “Martha,” the much-hyped Netflix documentary about her life that begins streaming Wednesday.

In promoting the film, Martha, 83, has admitted to cheating on Andy during their marriage. She boasts it was “very easy” to keep her claimed affair a secret from him for some three decades, advising viewers, “You have to be circumspect” — meaning being wary and unwilling to take risks.

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

Among other incidents, sources told me how Martha once ran off for a night with a handsome stranger she and Andy met on their honeymoon in England, leaving her groom shocked and forced to sleep alone. Later, she would allegedly host swinger-like pool parties — flirting and cozying up to male guests — at Turkey Hill, the Westport, Conn., estate made popular in her magazine, Martha Stewart Living, and on her TV shows.

“Men chasing Martha, or her involvements, real or imagined, was never a secret to Andy, or to the couple’s close friends back in the day,” alleged the insider. “Martha will do anything for the publicity factor and to stay in the public eye as she ages, even literally boasting publicly about cheating on her husband. It’s all very bizarre. Only a woman with little or no morality, with no respect for the sanctity of marriage, would brag like that just to hype a film about her, and get media attention.”

Married in 1961, the Stewarts 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 80s, subsequently married Martha’s assistant Robin Fairclough but that union, too, ended in divorce. He’s now married for a third time, while Martha has remained single.

Martha would allegedly denigrate him in front of others, calling him “boring, disgusting, oafish,” and treat him more like a reviled servant than the husband who many considered to be the brains behind Martha’s early publishing successes, according to sources.

During one of those verbal fights, as detailed in my book, Martha claimed she had slept with another man while on a business trip to Los Angeles. Andy was shocked, but Martha dismissed the claimed tryst as “a one-time thing … unimportant … uninteresting … merely an experiment.”

But others in the Stewarts’ orbit back in the day, such as the writer Jonathan Fast, third husband of novelist Erica Jong, were aware of Martha’s playing around — sometimes in the hot tub outside Fast’s bedroom.

“People were cavorting naked,” recalled a male friend of Martha’s about those gatherings. The same kind of kinky activity occurred at the Stewarts’ home.

On one occasion at Turkey Hill, Fast recalled, “Martha spent the whole evening flirting with a very good-looking and very successful married banker. The flirtation was extremely blatant and aggressive. I felt left out because Martha wasn’t flirting 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 bitch.”

While Martha has recently boasted that she kept an affair secret from Andy “for 30 years,” Erica Jong, who had been a classmate of Martha’s at Barnard College, believed otherwise.

“I always heard that she was involved with people, that she was having lots of affairs,” Jong asserted.

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

During her rise to the top, Martha became a stockbroker for a time, and used her feminine wiles and her “great legs,” as one associate recalled, to generate business. One who flipped for her was a married stockbroker and co-worker, 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 keep his eyes off of her. “In those days, she was skinny and gorgeous, and extremely sexy,” Dennehy said.

While Dennehy claimed they never had an affair, he acknowledged, “I would fantasize about being involved with her.”

Andy allegedly suspected his wife’s boss, Andy Monness, of the firm Monness, Williams & Sidel, also had a “thing” for Martha. Monness denied any sort of affair, accept to rave about her: “Martha was my dream girl. She had the magic.”

At one point, fed up with her teasing and flirting, Andy allegedly had to confront one of Martha’s more avid pursuers, millionaire Andrew J. Stein, who once ran unsuccessfully for mayor of New York. Stein told me he sent her flowers and taken her out for drinks at Raffles, a romantic private club at the Sherry-Netherland Hotel.

Stein called it “playful flirting,” and Martha was flattered by the attention. He thought she had a “great look, and her response to me was friendly enough.”

But a fuming Andy had finally had it. When Stein went too far with his calls to Martha, he told me, Andy finally got on the phone with a warning: “Keep the f–k away from my wife!”

And Stein did.

Later, as a divorcée on the hunt for Mr. Right, Martha pursued her old stockbroker pal Dennehy, by then a successful actor, apparently hoping for a relationship.

“I felt she had this fantasy of hooking up with 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.”

By chance, Martha ran into him in New York.He found her even more “vivacious” than ever, and took her to a premiere and after-party.

“To have her on your arm is not such a bad thing,” Dennehy recalled.

But it was never anything more than that.

Why?

As Dennehy told me: “Martha is one of those women who intimidate the shit out of men.”