When Debra Newell first spotted John Meehan on a dating website in 2014, she was instantly smitten — but the mother of four couldn’t have predicted that her whirlwind romance would quickly unravel into a horrifying nightmare.

Newell’s case of love gone wrong is the subject of an upcoming Oxygen documentary titled “Dirty John: The Dirty Truth.” It features interviews with detectives who worked on the case, some of Meehan’s former girlfriends and even his first wife, Tonia Bales.

The shocking tale was the subject of a smash-hit podcast in 2017 – from Wondery and the Los Angeles Times – and, more recently, in late 2018, Bravo premiered “Dirty John,” a scripted series with Connie Britton in the starring role.

“I felt that the reason I participated in all of it, not just the Oxygen special, was to get awareness out there for other women,” Newell told Fox News.

Newell, who was four times divorced, met Meehan on an over-50 dating website. Meehan posed as an anesthesiologist who’d just returned to Southern California after a year in war-torn Iraq while volunteering with Doctors Without Borders.

Newell, a wealthy and successful interior designer ready for romance, was impressed by what she read and saw.

“What drew me into John was number one his love for animals,” explained Newell. “That he loved children. He … was good looking in my eyes. He was a doctor. Basically, he checked all the boxes for me.”

After two months of dating, the couple got married.

“John was extremely persistent,” said Newell. “Every day, he was saying, ‘Please, please, please marry me. You are my soulmate. You are the person that I want to live the rest of my life with. We’re getting older. Let’s just do it.’ I was nervous, apprehensive about doing it, but I did.”

While Newell said she felt herself quickly falling in love with the charismatic doctor, her four children weren’t impressed. In fact, one of her daughters hired a private investigator to confirm her fears. It turned out Meehan never worked for Doctors Without Borders and never even attended medical school.

What Meehan did have was a felony rap sheet, which unveiled he served time for stealing narcotics in hospitals. The Los Angeles Times reported that from 2005 to 2014, he had “seduced, swindled and terrorized multiple women, many of whom he had met on dating sites while posing as a doctor.” Newell said the report made by the private investigator was about 324 pages.

The newspaper added that by the time Meehan married Newell in December 2014, three women had standing restraining orders against him. At least three others had requested them. Meehan had also told Newell one of his sisters had died of cancer. However, both of his siblings were alive and well.

“I think that I jumped with my heart instead of my head, and I ignored the flags,” Newell admitted. “They were in front of me, but I refused to really look at them. I was just falling in love. … I wasn’t happy with how he was treating my kids. But I wasn’t seeing a lot of it because how he would treat them when I wasn’t around was very different when I was around … he didn’t make an effort to get to know my family, get to know my friends. He just wanted to be with me, and I thought that was one of the biggest signs.”

Newell said she thought then of her sister, Cindi Vickers. Oxygen shared that in 1984, Vickers’ husband Billy came up behind her, placed a pistol to the back of her neck and shot her to death. After pulling the trigger, Billy then shot himself in the stomach. He would survive the gunshot and later remarried.

Newell immediately wanted to end the marriage, even though Meehan kept insisting he was innocent of the allegations. They reconciled briefly, but eventually, she realized she couldn’t spend the rest of her life with a manipulative con artist. Newell filed to annul the marriage to Meehan in April 2016. She also went into hiding.

“I gave John a chance. I also had one foot in, and one foot out. I really needed to analyze and figure this all out on my own,” she recalled.

“When I left I had an exit plan because you don’t walk away from these men without something violent happening,” said Newell. “I had another phone. I had changed all my passwords. I changed emails. I had transferred money. I had talked to my office that I was going to be gone so they could get a hold of me remotely. There were many, many things I did to prepare myself to leave so that I could go into hiding.”

People magazine reported Meehan filed for divorce himself, demanding half of Newell’s income and ownership in her business. He also reportedly lit her Tesla on fire, emailed nude images of her to her family and began to stalk her.

“I thought he was after me for my money, so I didn’t feel that my kids should be in fear,” said Newell. “We thought it was me, and so I’d been hiding for seven months at this point.”

Then on Aug. 20, 2016, Meehan waited outside of her youngest daughter, Terra’s, apartment and attacked her with a knife. An injured Terra, who was inspired by moves she saw on “The Walking Dead,” managed to fight Meehan off her. She kicked the knife from his hand, grabbed the weapon and stabbed him multiple times.

“She was right-handed. She didn’t think,” reported the Los Angeles Times. “She began flailing, looking for targets. She connected, again and again. His shoulder. His shoulder blade. His triceps. His shoulder blade. His upper back. His shoulder blade. His upper back. Between his shoulder blades. His forearm. His triceps. His shoulder. His chest. His left eye — and through it — into his brain.”

Newell would receive a phone call from a distraught Terra.

“I get this call from my daughter, and she’s screaming that she killed my husband,” said Newell. “It was so surreal. The guilt and just everything overwhelmed me. … I don’t know how I got there, but I got to the site … She was sitting on the curb. I just wanted to be with her.”

Meehan died in the hospital four days later. Newell said she and Meehan were separated at the time. She claimed their annulment was going to be final on Sept. 13.

The then-25-year-old Terra was never charged for Meehan’s death because it was determined she fought back in self-defense. Newell also shared Terra was sent away for about six months to Austin, Texas, where she received extensive therapy for PTSD. But before then, Newell reached out to Meehan’s sisters to notify them of their brother’s fate.

“When everything happened we actually called John’s sisters,” said Newell. “They talked about the fact that they had been in fear, and that they were OK with what Terra had done. … The girls had relief. They were many, many other victims out there that were all of a sudden no longer in fear because John was gone.”

Newell said she hasn’t dated since. These days, she’s hoping her story will educate others on how easily one can be tangled in a terrifying situation if those glaring red flags are ignored.

“I hope people understand that it can happen to anyone,” said Newell. “There are many, many people out there that are going through what I went through, maybe in a different way. But they are not alone.”

“Dirty John: The Dirty Truth” airs Jan. 14 at 8 p.m. on Oxygen.