Gavin "Scott" Hapgood, a USB financial adviser who is accused of killing a hotel worker while on vacation in April 2019

Kallie Hapgood, wife of Scott Hapgood, with their three children (from left): Hope, Winn and Ryan.

It was the first international trip Kallie Hapgood and her husband, Scott, had ever taken with their three kids in tow, and it was a dreamy one — six carefree days at a lush resort on the tiny tropical island of Anguilla.

Less than 48 hours into her picture-perfect vacation, the Darien, Connecticut, mom heard three words that nearly tore her family apart.

The 44-year-old mom was returning to their suite after a morning snorkeling and lounging in the Caribbean sun — the start of a much-needed break from her demanding job as a managing director at a prestigious private equity firm — when she saw her then-13-year-old daughter running through the lobby of the Malliouhana resort.

Her eyes were wide with panic.

“Dad’s been stabbed!” the terrified teen screamed.

Worst case was all Kallie could think.

“I was so fearful that my husband had passed away,” she told The Post in an exclusive interview, her first since the Saturday exactly six months ago when the family’s idyllic life unraveled.

“I ran, and I was so thankful that he was alive,” she said.

But Kenny Mitchel — the allegedly drug-crazed hotel worker Hapgood says he fought off after he showed up to their room unannounced, pulled a knife and demanded cash — didn’t survive the altercation, and Hapgood has been charged with manslaughter in connection with his death.

The case has dominated the news cycle on the island, where residents were angered that Hapgood was released on bail. Locals have fiercely defended Mitchel, gossiping about the Hapgoods and spreading rumors what happened inside Room 49 at the Malliouhana resort.

Kallie said she and Hapgood have received multiple death threats, and she once called the local Darien police after an anonymous call came to her desk phone at work while Hapgood was in Anguilla for a hearing.

“There was a really scary laugh on the other end,” she said. “Like a malicious laugh.”

The family also suspects a Mitchel supporter reported her husband to local child services. Officials grilled the couple and their kids in a series of home visits, she said.

The ordeal, which requires Hapgood to return to Anguilla regularly for court hearings, has only brought the couple, together for 25 years and married for 17, closer, Kallie said — except when it comes to one issue.

“We are in lock step together aside from the fact he keeps wanting to return, and I don’t want him to,” she said.

Kallie prefers Hapgood risk arrest by American authorities and extradition to Anguilla, rather than continue returning there for court appearances — where he could be jailed in a prison guarded by some of Mitchel’s relatives.

“I have begged him from day one not to go back there, and I still don’t want him to go back there, but he needs to make his own decisions, and he feels strongly about clearing his name,” Kallie said. “He knows he did nothing wrong. He’s not responsible for Mitchel’s death, but to me, I don’t know if that is enough to keep him safe. If he were to be remanded to prison, I think it would be the equivalent of a death sentence.”

His lawyer, Juliya Arbisman, vows he will return.

At the forefront of Kallie’s mind when she considers her husband’s safety on the island are the harrowing hours he spent inside an Anguillian jail cell shortly after he was denied bail on April 17, a decision reversed by a higher court.

“That might have been the worst part of that trip to Anguilla,” she said. “Even worse than being attacked. He sat there for six hours and listened to people yell at him and tell him how they were going to kill him, and he wasn’t going to make it through the night.”

For an Ivy League grad who has never been involved in the criminal legal system, the experience was “surreal,” Kallie said.

After meeting her daughter in the lobby, once Kallie was reunited with her husband back in Room 49 and saw what had happened between Hapgood and the hotel worker — the details of which she declined to discuss with The Post, citing the ongoing criminal case — she “begged” hotel staff to call the police.

When they finally did arrive, after what seemed like hours, a female officer relayed an ominous message that has stuck with Kallie as her distrust for island authorities has grown over the past six months.

“She looked at me and said, ‘We know him. He is a bad guy. He was just in our custody,’” Kallie said.

Once Mitchel’s death was made public, reports surfaced that he was arrested and accused of raping the mother of his children, Emily Garlick, in March. Garlick later claimed it was a misunderstanding.

Considering the charges against Mitchel, which were pending at the time of his death, “I don’t understand why the hotel thought it was OK for him to be around my children or me and my family,” Kallie said.

A toxicology report showing Mitchel died from a lethal amount of cocaine in his system, opposed to the original ruling that it was a result of injuries sustained during his fight with Hapgood, has only solidified her husband’s innocence in Kallie’s mind.

“My husband was defending himself and our two young daughters against somebody who was drunk and high on cocaine and lied to get into our hotel room,” she said. “That gentleman passed away from the amount of cocaine he had in his system.”

But the prosecution’s handling of the findings, made public Oct. 1, has made her even more skeptical of the legal process in Anguilla.

Kallie claims “the prosecution waited two months before they sent the blood out for toxicology, and they got the preliminary results back in June. They didn’t provide those to us or to the original pathologist for another two months.

“So for Scott to go back down there and continue to defend himself … I just … the deck is stacked against him.”

Before the ordeal, the Hapgoods’ lives were a picture postcard of all-American suburban utopia.

The couple met at Dartmouth in the ’90s, where the 6-foot-2, 240-pound Hapgood played as a defensive end on the football team and Kallie was captain of the tennis team.

After graduation, the couple settled in Darien, Hapgood’s hometown, where he set records as a lacrosse player at Darien High School, before attending boarding school in rural Watertown. Hapgood’s parents still live nearby, and his father is a fixture at the kids’ sports’ games, Kallie said.

Both Kallie and her husband pursued careers in the financial industry, and in 2003, they were married. Three years later, Kallie gave birth to their first daughter, who is now 14, before they had a second girl, 12, and a son, 9.

They spent their days in the office — Kallie at Gridiron Capital and Scott at UBS Investment Bank — and their weekends on the sports fields, at their kids’ lacrosse, field hockey and football games, Kallie said.

Throughout the past six months, they have watched their savings dwindle on legal fees as the angry rumors of Anguillans laid waste to Scott’s reputation.

In recent weeks, on the “Unity for Justice” Facebook page dedicated to Mitchel, his backers began to float the idea that Hapgood was buying cocaine from Mitchel — a suggestion Kallie firmly denies.

“The idea that my husband was buying drugs off a hotel employee in a five-star resort in front of my children is ludicrous,” she said. “My husband does not do drugs.”

In another blow, Hapgood recently learned he would not be able to coach their son’s football team due to the charges.

On leave from UBS, Hapgood spends his days on the phone with lawyers and writing thank you notes to supporters, Kallie said. He finds relaxation in bonding with his English bulldogs, Patriot and Cobber, cooking for his family and the occasional game of paddle tennis, she said.

“He is home, and it’s really lonely,” said Kallie, who describes her husband as “an amazing person. He is gentle, he’s kind, he’s thoughtful, he is a wonderful person. His No. 1 priority in life is his children and family time.”

A bright spot amid the “dark cloud that has been hanging over our heads,” Kallie said, is the outpouring of support from the Darien community.

At the Hapgoods’ first public event since Mitchel’s death, their daughter’s lacrosse game, “it took us 20 minutes to get to the field, because we were getting hugs and well wishes,” Kallie said.

A GoFundMe page started for the couple by friends generated more than $250,000 in donations in six days before the campaign was pulled for violating the site’s policy against fundraisers for people accused of violent crimes — amid an outcry from Mitchel’s supporters that the page be taken down.

Scott signed a declaration that he would not use the money on legal fees, and the cash was released earlier this month, Kallie said. The family is using the GoFundMe money to pay crisis management firm Infinite Global; for private security for Hapgood while he is on the island; therapy for him and their daughters; and travel expenses to and from Anguilla, she said.

“We are so thankful and grateful for those funds,” Kallie said. “We desperately needed them.”