The former aide to the British royal family found dead in Dallas last week was married to a manipulative man whose charm reminded her family of a serial killer, her sister told The Post Monday.

Jenean Chapman had only been married to “short, fat, bald” James Patrick for a couple of months before her dead body was discovered in her apartment last Monday according to Charene Chapman-Santiago.

Patrick has since been arrested in Austin and will be sent back to Dallas where authorities will charge him with murder after he allegedly strangled her.

Chapman-Santiago told The Post the couple never quite fit — Chapman, 46, was an intelligent, well-traveled, cosmopolitan go-getter who had previously worked for Sarah Ferguson, the Duchess of York, and hip hop mogul Russell Simmons.

Meanwhile Charene said her 48-year-old husband, James Patrick, was a perennially out-of-work layabout who cloaked his possessive and violent tendencies behind a charming facade.

“Jenean was charmed by his magnetism,” she told The Post by phone Monday morning as she packed up her late sister’s apartment.

“He was like Ted Bundy — people thought he was very charming,” said Charene, 48, who lives in Brooklyn. “I saw through it, though. I never liked him.”

Serial killer Bundy, who was executed in 1989, was said to be charismatic and personable to those around him, as well as a master manipulator.

Cops found Chapman dead on Sept. 25 in her downtown Dallas apartment at about 1:15 p.m. after they were asked to do a welfare check, the department has said.

The following day, medical examiners in Dallas County ruled her death a homicide — and cops fingered Patrick as their main suspect.

He was arrested by police at the University of Texas in Austin. It is unclear if he has a lawyer to represent him.

Other family members have also described Chapman and Patrick’s relationship as difficult and toxic, including Chapman’s sister, Nicole.

“It was rocky, we were aware of that,” Nicole told BNC Dallas Fort Worth. “She broke the news to our mother (about the marriage), and of course our mother told us and yeah, we definitely didn’t see that coming. And no, there was no wedding.”

“We were shocked because before that, it was an on-and-off relationship,”

Charene expanded upon that, further detailing the twisted lengths the controlling Patrick would allegedly go in his attempts to control Chapman, a New York native who graduated from Syracuse University.

“She loved James — she loved him completely,” Charene said. “Even though he mistreated her, she wanted so much to make it work.”

The couple met in San Francisco in 2018 and eloped in July, even though Chapman regretted not having a more traditional ceremony.

“She wanted the engagement ring and the dress and her family — but he pushed her,” Charene said.

Charene also said she immediately disliked Patrick, whom she found to be arrogant and obnoxious. She added how her impression was that he felt like he was doing her sister a favor by being with her.

“Even though he was a short, fat, bald man, and she was a beautiful queen,” Charene said. “They didn’t match.”

Patrick was constantly getting fired from jobs and cheated on Chapman at least once, she claimed.

Meanwhile, according to Charene, Chapman — a senior vice president at Critical Mass, a digital marketing firm —supported him financially.

“He was extremely possessive,” Charene said. “He would accuse her of cheating, but he was doing the cheating. He was the epitome of a gaslighter.”

That wasn’t who she wanted for her sister, whom Charene described as “the most generous person I’ve ever met.”

“Jenean would do anything for anyone,” Charene said. “She was kind, sensitive, funny and quick-witted.”

“People keep talking about how she was the assistant to the Duchess of York, but that was 20 years ago,” she continued. “She was the senior vice president of a company in Texas — as a black woman. I was so proud of her.”

Despite Charene’s dislike of her sister’s husband, she only found out about alleged physical abuse a few weeks ago.

“I begged her to come and live with me,” Charene said. “I said I wouPaatd sleep on the floor if I had to, I just wanted her to get out. I said I would come to Texas, but she said, ‘Don’t come.’”

Charene listened when Chapman said to stay away. Now, her decision haunts her.

“I should have gone to save my sister,” she said. “I will always regret not saving her in time.”