Now that she’s pregnant with Simon Cowell’s baby, scheming Manhattan social climber Lauren Silverman wants the filthy-rich “X-Factor” mogul to marry her, sources said.

And Cowell – who has been named as a co-respondent by Silverman’s outraged husband Andrew in their messy divorce – has said he will do his baby mama’s bidding, according to the sources.

“He promised to marry her after learning she was pregnant, and she is trying to make sure she keeps his promise.” a source close to the situation told The Post today.

“Simon says he will do the right thing for the baby.”

SEE PICS OF LAUREN SILVERMAN IN THE HAMPTONS

Cowell and Lauren had been carrying on their illicit trysts for more than a year, right under the nose of spurned spouse Andrew, several sources noted.

“She was sleeping with him on his yacht, while Andrew was there,” said one insider.

A few months ago, Lauren boldly posted photos of herself in a bikini, snuggling with Cowell on his yacht, with the caption, “Me and my little Simey monster.” She recently deleted the shot, and several others of herself with Cowell, from the social media site.

When Page Six asked Lauren about the photo and her alleged affair in May, she burst into tears and said, “Simon is my best friend, but please don’t write we are having an affair…it would destroy my family.”

Lauren had pretended to treat Cowell as just a close pal as they yachted and hobnobbed together — only to blindside her real estate developer husband Andrew, 37, well after the affair was in full swing, sources said.

“It is an unbelievable story of betrayal. It is a sad story and a tragic story,” Andrew’s brother, Alexander, told The Post.

One friend of the shapely brunette said that the Silvermans “weren’t estranged, as some friends of Lauren have claimed.

“The suggestion that she was an estranged wife who fell into another man’s arms is not the case.”

In fact, Andrew had been so oblivious to the sordid, under-his-nose affair that he recently upgraded Lauren’s engagement ring with a 10-karat diamond, a friend said.

“She is a total gold digger,” one pal said.

Another added, “The pregnancy was by design.”

Andrew is so livid, he’s seeking revenge on both Cowell and his straying wife — who is 10 weeks pregnant with Cowell’s baby. He’s taking the highly unusual step of embarrassing Cowell personally by naming him as a co-respondent in divorce papers, which were filed under the radar in Manhattan Supreme Court two weeks ago.

New York is a no-fault divorce state, but Andrew has filed for a fault divorce based on adultery.

That means Cowell, 53, risks being hauled to the witness stand to reveal his finances — he is said to be worth about $350 million — in addition to the sordid details of his affair with Silverman.

“It’s really a signal to the spouse who cheated that the wronged spouse is very angry and that it’s going to be a very nasty, scorched-earth, high-profile litigation,” said noted divorce attorney Martha Cohen Stine.

Another top matrimonial attorney agreed that the rare move was a pressure tactic.

“It’s very nasty,” said William Zabel, billionaire George Soros’ attorney. “I assume it’s to embarrass them and get them to settle.”

Cowell and Lauren Silverman had met on vacation seven years ago at the exclusive Sandy Lane resort in Barbados. Silverman dutifully introduced Cowell to her husband.

The Silvermans and Cowell — who was squiring English presenter Terri Seymour at the time — hit it off. They double-dated and vacationed together frequently, remaining close as Cowell traded in Seymour for his next, long-haired brunette gal pal, makeup artist Mezhgan Hussainy, who would become Cowell’s fiancé.

The married Silvermans and the engaged Cowell and Hussainy were even photographed frolicking together on the X-Factor judge’s yacht in St. Barth’s in January 2012 as if everything was fine and faithful — even though by then their extramarital treachery was in flower, a friend of Lauren’s said.

Andrew and Lauren had lived together in their Upper East Side apartment until June, when she moved out to their home in Bridgehampton with their 7-year-old son, also named Andrew, to spend the summer near the beach.

Her friends say she’s “overjoyed” by the pregnancy and Cowell can’t wait to be a father.

“He’s thrilled,” one friend said, adding that he traveled to Miami to meet Lauren’s parents.

Lauren and Cowell have lawyered up, hiring the high-powered divorce team of Bernard Clair and Robert S. Cohen.

Lauren’s husband, Andrew, comes from a moderately wealthy real-estate family, although, compared to Cowell’s massive fortune, he’s a small fry.

“He’s just an average guy from a real- estate family,” said one realty source.

Andrew works for The Andalex Group, founded by his father, Allen Silverman. Andrew, along with his brother, Alexander, have been called rising stars in New York’s real-estate industry.

The company, however, ran into some problems with a marquee project in Long Island City, Queens, where it spent $130 million converting a former electric factory into luxury condominiums, according to published reports.

A group of condo owners in the Arris Lofts building filed a civil complaint in 2010 seeking $20 million in damages when they said the developer ignored repeated requests for repairs. The disposition of the claim was not known.

Andrew married Lauren while they were in their mid-20s.

“I always found her very pretty, but I found them to be very pretentious,” an acquaintance in the Silvermans’ social circle said. “And I always wondered why she married him, and I figured it was for money.”

Andrew was spotted running from his Midtown office to a car yesterday when reporters asked him for a comment.

Meanwhile, Cowell’s mother, Julie, seemed thrilled at the prospect of becoming a grandmother, telling The Sun newspaper in England, “I’m delighted. It’s wonderful.”

Rosy Davis, who is the wife of Lauren’s father, Steven, told Britain’s Daily Mail, “We are all excited for the baby. It’s beautiful. We feel blessed.”

Close friends of the Silvermans say the real issue is who will care for their little boy.

“How will all of this play out? That’s the really sad part,” a friend said.

Additional reporting by Tara Palmeri, Julia Marsh and Frank Rosario