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TEEN LOVER ‘COOKS’ CAD PETER

The doe-eyed beauty at the center of Christie Brinkley’s divorce case took the stand yesterday as the star witness and dished on the sordid affair that was ultimately the death knell for the supermodel’s marriage.

“We had been working together and he’d shown interest in me and I had reciprocated,” the now 22-year-old testified about her steamy year-long affair with architect Peter Cook.

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Bianchi – who hunched over in a vain attempt to hide from the stares of the entire courthouse as she clutched her mother’s arm and even wore a rosary on her wrist – never painted herself as a victim of Cook’s wily charms, instead she categorized the feelings as mutual.

“He asked me how I would feel if he told me he was attracted to me,” she said before admitting, “I was a bit taken aback, but I really wasn’t against it.”

Wearing a short-sleeved, frilly white blouse and a demure, long gray skirt, Bianchi spoke with a tiny, shaken voice as she recounted the intimate details of their tawdry trysts and the money he showered her with.

She countered Cook’s claims from earlier in the day that he once hid $500 under a rock near his office in Southampton. Instead, she said it was under a rock at the Bridgehampton home he lived in with Brinkley and their kids.

Cook also testified that he only gave Bianchi $20,000 as part of her official duties pushing papers at his office, but Bianchi claimed he doled out an extra $15,000 for a down payment on a new Nissan Maxima in 2005.

“I didn’t know how to buy a car so he basically just walked me through the process,” she said under questioning from Brinkley’s lawyer, Robert Cohen.

Asked if Cook bought anything else for her, Bianchi described him as a dutiful sugar daddy.

“Yes,” she said, “Just odds and ends, things that I needed – If I had a problem, if I was in a bind, he would help me out.”

But she claimed, “I would not be able to give you specific amounts.”

That was before Cook paid her $300,000 in May 2007 to keep mum about their relationship – a hush-money sum The Post reported last week.

She said she met Cook when she was just a 15-year-old clerk in a toy store in 2003.

In the summer of 2004, they talked on the phone – and she said she even sang for him.

“He just said I had a great voice and it was something I should pursue,” said Bianchi, who is trying to make a go of a music career.

The two had nothing to do with one another

When she ran into him a year later, Cook slipped Bianchi his card – which the teen thought was innocent enough.

“If someone gives you their business card you assume it’s [just] for business,” she said on the stand.

In 2005 Cook hired the young stunner to work at his Hamptons architecture firm when she was just 18 and looking for some extra money.

Bianchi couldn’t recall what she did, exactly, or how much she was compensated.

Despite not having any experience besides selling toys and baby-sitting, Bianchi said she was paid “anywhere from $20 to $50 an hour, depending on how much I got done.”

That response elicited chuckles from the courtroom.

When Cohen pressed Bianchi for more details about how much she “got done” and how much she was paid, she was fuzzy about the details.

“He asked, basically, if I would help him with things like paperwork. I don’t remember exactly what it was, just office work and keeping things up to date and stuff like that,” she said.

After months of flirting – they finally had sex that spring, she testified.

But she denied Cook’s claim that she just stripped and asked for sex one day.

“I would say it was a mutual thing,” said Bianchi. “The first time was in his office.”

Bianchi recalled a couple less liaisons than the dozen times Cook said he bedded her.

“Ten, at the most, I would say,” Bianchi remembered.

Cohen also confronted Bianchi with an e-mail sent to her by Cook, stating, “you need to call me, your stepdad is out of control,” and other missives saying they need to get their “stories straight.”

Asked if that meant he wanted her to lie, Bianchi said yes. Cohen then asked her if she did, in fact, lie to her parents afterward, and she responded, “yes.”

Later on the stand, Bianchi’s stepdad, Brian Platt, described telling her of the affair at the 2006 graduation ceremony at Southampton HS, where Brinkley gave the commencement address. “She was obviously shaken,” Platt said. He said when he outed Cook in front of his wife, the architect “looked like he urinated in his pants. I did tell him that his day was coming and it was coming pretty soon,” said Platt.

selim.algar@nypost.com