She claims to be a great advocate for human rights — but former employees tell The Post that behind closed doors, Kerry Kennedy is a monster who’s driving her father’s legacy into the ground.

“For someone who’s a human-rights lawyer, I don’t think I’ve ever met someone who cares so little for the people who work for her,” says an employee who resigned from the Robert F. Kennedy Center for Justice & Human Rights. “She treats them so badly, belittling and embarrassing them in front of others. Everyone who works there is brilliant, but there is very high turnover.”

In the past year, sources say, at least nine employees have quit.

Several ex-employees also tell The Post that Kennedy, who serves as president of the center, has grown increasingly erratic. “She’s unhinged,” says this same employee. “Bitter. She can’t follow up and can be very vague. Sometimes she would get frustrated but couldn’t convey where her frustration was coming from.”

“Her priorities can change on a whim and her mood,” says another, who held a high-ranking position for 3¹/₂ years. “It made me feel like a crazy person. I’d heard stories that Kerry was a loose cannon, but her crazy behavior ramped up in the beginning of 2015.”

Kennedy, 56, is the seventh child of Robert F. Kennedy and the ex-wife of Gov. Cuomo. As head of the RFK Center, a nonprofit with the vague stated goal of “rais[ing] awareness of the most important — and sometimes overlooked — human-rights challenges,” Kennedy presents herself as a standard-bearer and champion of the world’s most abused citizens.

These ex-employees say Kennedy herself behaves like the dictator of a banana republic, sending some to perform menial personal tasks rather than respond to desperate e-mails from the world’s most dangerous hot spots.

“In general, she treats everyone as the person who would go get her coffee,” says another former executive. “Her attitude is, ‘You’re here to do what I want you to do.’ RFK surrounded himself with people who would say no and push back against him. She surrounds herself with people who won’t challenge her and who say yes no matter what.”

These employees could never figure out what the foundation’s goals were.

“It is the most dysfunctional and disheartening organization,” says a former policy worker who left recently. “Especially given Kerry’s image, and the public image of the organization. They don’t even care about the dignity of their own employees.”

‘She has truly become unhinged, and people don’t know what to do.’ - A source tied to the RFK Center for Justice & Human Rights

This employee says he went to his supervisor — a close friend of Kennedy’s — with a written complaint about lack of leadership. This employee had been tasked with human-rights work in numerous nations with no help.”

“I tried to raise concerns, and he said, ‘I’m not gonna do that.’ He literally threw my prepared paper on the floor and went back to sending e-mails or whatever. It was the most disrespected I’d ever been in my entire career.”

Multiple sources — all of whom spoke on the condition of anonymity — say Kennedy uses foundation funds to pay for lavish expenses and the foundation itself as an excuse to party with celebs around the globe. The foundation’s most recent tax filings show she paid herself $357,340 in 2014. That same year, she took out a $2.4 million line of credit for the center, which has offices in DC and on Manhattan’s Madison Avenue.

In November 2015, she sold her house in the Westchester town of Bedford for $920,000. There is no public record of her having purchased another residence.

“She has truly become unhinged, and people are frozen and don’t know what to do,” says a source who e-mailed The Post. “Her staff fear her, as she has a wicked temper and is quite entitled and belligerent — but now they fear for her, as she has become difficult to follow . . . She has become bitter, mean and angry — and now, clearly, publicly depressed.”

Kennedy did not return repeated requests for comment.

The past few years have been difficult for Kennedy. Her best friend and sister-in-law, Mary Richardson Kennedy, hanged herself in her barn in May 2012. Mary was battling her estranged husband, Robert F. Kennedy Jr., over his serial cheating and public affair with actress Cheryl Hines. Mary and RFK Jr. were also engaged in a custody battle over their four kids, and after Mary’s suicide, Kerry — who had abandoned her to side with her brother — wrote a piece for The Huffington Post.

It was called “Ode to My Best Friend,” and in it, Kerry wrote, “Like millions of Americans, Mary suffered from depression . . . Mary fought back the demons who were trying to invade the Paradise of her very being.”

In 2013, Kerry told The Daily Beast that “Mary’s was a classic mental illness,” infuriating the Richardson family. One relative told the site that the Kennedy propaganda machine had been spreading “vindictive lies, proof of the unbelievable emotional and psychological abuse that Mary endured in the last years of her life, and now, in death.”

Two months after Mary’s suicide, Kerry was arrested for driving while impaired. She had smashed into a tractor-trailer on I-684 and fled. She claimed to have taken only an Ambien and, on the witness stand, told the court of her human-rights work. She was so anxious about an imminent aid trip to Uganda, she testified, that she mixed up her meds.

The jury took an hour to acquit. Kennedy then went on the “Today” show to complain about her treatment by the criminal-justice system. “[It’s] a terrible policy . . . pursuing every case of driving under the influence,” she said.

In 2014, say multiple former employees, Kennedy hit up wealthy donors to bail out the RFK Center, which still suffers from Kerry’s spending sprees.

Proximity to wealth and fame is Kennedy’s priority, with human rights nowhere on the radar. - A source close to the Kennedys

“On a trip to France, we stayed in the same hotel John Kerry was staying at — a $500-a-night hotel,” says a former center executive. “They always fly business class. Or Kerry will book a plane ticket and change her mind at the last minute, and you’ll have to buy a totally new ticket.”

The purpose of the three-day Paris trip, says the exec, was to screen a movie with actor Javier Bardem.

“There’s always random celebrities around,” says the exec. “The organization most heavily benefits the family. Her South Africa trip” — this past June — “was ostensibly to ‘honor the legacy of her father and the ending of apartheid.’ She gave a speech. Those all end up being travel parties for her family.”

This source says Kennedy took one of her teenage daughters to build houses in Mexico because the girl wanted to write a piece for Teen Vogue — which never ran. “We don’t build houses,” says the former exec. “That’s not our mission. Why? Habitat for Humanity exists. We’re a bunch of lawyers and policy people.”

Kerry’s actual role is unclear. “She’s RFK’s daughter — that’s largely what she brings to the table,” says this source. “I don’t think she’s very talented. I don’t think she’s very bright.”

“I can’t recall seeing her read a newspaper or a magazine,” says another ex-employee. “She spends all day on the phone. She writes a lot of thank-you notes to people who’ve donated money. She’s constantly trying to get celebrities and throwing celebrity gala events. I asked the question while I was there: ‘Who are we helping?’ I don’t know.”

This source also says Kennedy “always stays in really nice hotels — four star. Car services. Sometimes she would stay in really rich people’s homes.” Proximity to wealth and fame, says this source, is Kennedy’s priority, with human rights nowhere on the radar.

“It’s just her lack of compassion,” says this source. “I just feel like people who are bright and with it have compassion and empathy . . . It was a very tense environment. I just said, ‘Life is too short — I’m not going to keep living like this.’ ”

Kennedy has spent the past few weeks traveling, and her Twitter feed indicates she attended something called the Ischia Global Film & Music Festival in Italy on July 10, after speaking in Paris on July 9.

“Me speaking today at the Free Iran 2016 conference in Paris,” she tweeted. “So many really interesting people! #freeiran.”