It was a story that generated headlines around the world. A young pregnant American woman Caitlan Coleman and her Canadian husband Joshua Boyle captured by the Taliban while hiking in war-torn Afghanistan. Grainy hostage videos posted online showing two of their young children born into captivity. And in 2017, the sudden release and return of a family of five to Canada, where a baffled public was eagerly awaiting an explanation.

But in the months following their liberation, they struggled to answer key questions – Why had a pregnant couple travelled to a dangerous region of Afghanistan, and why did they continue to have children even after they were taken prisoner there? – that had confounded even the closest observers of their case. Until now.

Having finally fled from Canada to the United States with her four young children, Coleman can finally say what many previously suspected – that she was a prisoner not only to Islamic militants, but also to her own husband. In an exclusive interview airing tonight on "Nightline," Coleman told ABC News that Boyle was a Taliban sympathizer, and he gave her “no choice” but to accompany him to Afghanistan, where he subjected her to years of “extreme” abuse during their captivity in Pakistan.

“Not only was it psychological, it was physical, it was sexual," Coleman told ABC News. "I was actually more afraid of him than of the captors."

Watch the full story on "Nightline" TONIGHT at 12:35 a.m. ET

The alleged abuse, Coleman said, continued after they returned home. Boyle was arrested by Canadian authorities on Dec. 30, 2017 and charged with 19 criminal violations, including repeatedly assaulting, raping, drugging and unlawfully confining his wife, all of which allegedly took place after their arrival in Canada. Boyle has pleaded not guilty.

While his trial is on hiatus during appeals related to Coleman's testimony, she is speaking out for the first time about what she described as a dizzying web of lies Boyle has told to protect himself as he sought to keep her quiet about the full extent of her ordeal.

"He restricted pretty much everything," said Coleman of her life with Boyle in Canada. "I had no freedom, as far as, you know, where I would go, who I would talk to, how I would dress, what I would say."

In response to questions from ABC News, Boyle's criminal defense attorney Lawrence Greenspon declined to comment.

In the months following the couple’s release and return, Boyle has given shifting explanations for his reasons for traveling with Coleman, then six months pregnant, to Afghanistan in 2012.

At a press conference shortly after their arrival in Canada, Boyle suggested that they had been aid workers, “engaged in helping ordinary villagers in Taliban-controlled regions of Afghanistan,” though they had no affiliation with any aid groups and no prior experience in humanitarian work.

He later claimed, in their child custody case, to have dreamed of being a "war correspondent," so he entered Afghanistan "in hopes I could meet people who could give me a story I could write about,” though he had no affiliation with any news organization and no prior experience in journalism.

And he has steadfastly denied supporting the Taliban, dismissing the suspicions of Western intelligence officials about his true loyalties as "off base” in a 2017 interview with ABC News.

But according to Coleman, Boyle was “sympathetic to the Taliban” when he told her in the middle of their South Asia hiking trip that they would “dip in” to Afghanistan for a few days. He assured her, she said, Taliban would welcome him "as a guest.” She did not want to go, she said, and she objected, but she was “not given a choice” by her husband, who was carrying their money and their passports.

Years earlier, Boyle protested the U.S. detention center in Guantanamo Bay, Cuba, and then was briefly married to Zaynab Khadr, the Canadian daughter of a senior al Qaeda aide to Osama Bin Laden. He expected that this affiliation would help him win the trust of the militants, Coleman said, and “sort of get the real story of the Taliban.”

"He would always tell me, 'I think they're misrepresented in the West. I think they're good people. When you meet them, you're gonna see,’” Coleman said. “So I saw. And they are, with the exception of my husband, the worst people that I've ever known in my life.”

They spent a few days in the Afghan capital Kabul before Boyle hired a taxi to drive them deep into Taliban-controlled territory. Armed gunmen on the road told their driver to pull over and took control of their vehicle. Coleman says Boyle frequently mentioned his former father-in-law, but their captors simply shrugged.

Taliban sources later told ABC News that the Haqqani Network, a notoriously brutal Taliban-allied militant group, purchased the couple "for a few thousand dollars" from the kidnappers who first abducted them and smuggled them into Pakistan. A few months later, Coleman would give birth to her first child, Najaeshi Jonah, now 6, in primitive and unsanitary conditions she described as “really, really scary.”

But even in captivity, where they lacked access to any basic medical care, their family continued to grow. Coleman miscarried their second child, which they named Martyr, after she says the guards put a chemical in her food. They had two more children in captivity (Dhakwoen Noah, 3 and Ma'idah Grace, 2) and became pregnant with another (Duhaa Joy, nine months) who was born after their release.

Hostage videos posted online by the Taliban in 2017 showed their two sons sitting on their parents’ laps.

After their release, Boyle offered his own explanation to the Associated Press: "We're sitting as hostages with a lot of time on our hands. We always wanted as many as possible, and we didn't want to waste time. Cait's in her 30s, the clock is ticking." But Coleman’s story is far more troubling. She claims her husband repeatedly raped her while they were prisoners of the Taliban.

"You know, I'm not saying that I physically struggled,” Coleman said. “But I am saying that I found relations with him pretty abhorrent. But I didn't have a choice."

As the years piled up, Coleman says, Boyle grew increasingly violent.

"The captors would sort of leave us alone," she said, but a "normal life" in captivity was impossible "because what I was going through inside the cell was too horrific."

In a 2017 interview with ABC News, Boyle claimed a guard had struck Coleman, breaking her cheekbone. The guards were sometimes rough, Coleman said, but “it was actually Josh who broke it, by hitting me.”

And the alleged abuse did not stop after their release and return to Canada.

"I certainly felt like I was still a prisoner,” Coleman said. “There wasn't actually a big change in my life from when we were still in Pakistan in the hands of the Haqqanis and when I was in the Embassy Suites Hotel [in Ottawa] with Josh.”

Then, in December, her husband having allegedly abused her one time too many times, she fled into the cold night, grabbing her children’s passports so they could not be taken overseas. Boyle called authorities and was later arrested by Ottawa police and jailed for months, during which time Coleman successfully argued in an Ottawa family court for full custody of their children, paving the way for her to return to the United States last summer.

Many current and former senior U.S. officials have told ABC News that they believe Coleman was the victim of both the Taliban and her husband, so they have strived to assist her since returning to the United States. And she has volunteered for extensive debriefings by both the FBI and the Department of Defense’s Joint Personnel Recovery Agency about her hostage ordeal.

Tom Bossert, a former homeland security adviser to President Donald Trump who once oversaw the Trump administration’s hostage recovery efforts, said the information Coleman has provided could prove extremely valuable.

“Despite wanting to put this ordeal behind her, Caitlan has spent time cooperating with authorities,” said Bossert, who is now an ABC News contributor, “teaching them about her captors and how we might save other hostages still suffering in captivity.”

Coleman said she still fears her husband and has asked that ABC News not reveal where she and the children now reside in the United States. Boyle’s trial – in which Coleman has already testified – is currently in a brief hiatus, but if convicted, he faces more years as a prisoner.

The future for Coleman and her children is uncertain. But Coleman knows, at least, that they are prepared to face it.

"We do have some ordeals ahead of us,” Coleman said. “But then I look at what I survived. And I don't think there's anything, you know, anything that I can foresee that I couldn't handle.”