'Assad's fall opened years of my husband's past I knew nothing about'

It was early December when Douna Haj Ahmed, a Syrian refugee, discovered the disturbing details of her husband's detention in the notorious Al-Khatib prison – known as "Hell on Earth".

She was watching bewildered prisoners fleeing the country's brutal security apparatus, on the news at home in London, after rebel forces had ousted Bashar al-Assad as president.

Through tears, Abdullah Al Nofal, her husband of eight years sat next to her, turned and said: "This is where I was arrested, this is the place."

Douna, whose brothers were also arrested during Syria's 13-year civil war, says she had an idea of what her husband experienced during his detention - but this was the first time he was sharing the full details of what he endured.

Abdullah was singled out at the checkpoint and put on a green bus, handcuffed and blindfolded, and taken to a military area. He says he was then put in solitary confinement for three days and beaten.

"It was so dark for three days, I remember," he says.

"I don't [hear] any sound. It was so dark. You hear nothing. You feel so lonely."

Abdullah was then transported to Al-Khatib, a detention centre in Damascus, and taken to a cell with about 130 people.

Al-Khatib was one of several detention facilities operated by Syrian intelligence services.

Almost 60,000 people were tortured and killed in the prisons run by the Assad regime during the civil war, according to the Syrian Observatory for Human Rights, a UK-based monitoring group.

Two years ago, a historic trial in Germany found a Syrian colonel who worked in Al-Khatib guilty of crimes against humanity. Anwar Raslan, 58, was linked to the torture of over 4,000 people in the prison.

In court, witnesses described how detainees were raped and hung from the ceiling for hours, as well as the use of electric shocks before being doused in water. Assad's authoritarian government previously denied accusations of torturing.

"As long as you say, 'I didn't do it', they will keep torturing you and they will take you to another stage in torturing," he says.

"Every minute it's like you're dying."

Abdullah says he told officers a false story to avoid further interrogation, and was "lucky" to be released from detention after a month.

Several years later, he left Syria and was later granted scholarships in Geneva and the US. He is now settled in London with his wife.

Only now does Abdullah feel able to share the full horror of his experiences with his wife, as the risk and fear he faced is slowly disappearing.

"We finally finish[ed] with the regime, we can say, we are really free right now," he says.

"You can use our name. You can use our face. We can tell the full story."

Douna, a human rights activist, sobbed as she heard her husband's experiences for the first time.

"I was hearing him and I was crying. Every time I feel that this regime [has reached] the maximum of the horrors, of the horrible stories," she says.

"It surprises me that, no, this is not the maximum. There could be more."

She adds: "We are privileged that we are able to tell our stories. Lots of people, they died without being heard."