(CNN) -- When he dreams, the prisoner is back in the dark at Guantanamo.
He is in a cell with a single tiny slit in one wall. He has been there for two years. In this nightmare, the one he endures repeatedly, he sings to himself, repeats lines from the Quran, rocks and murmurs. He sees his wife and small children like apparitions. They stand before him, but he cannot touch them. In his sleep, he is losing his mind again, kicking and punching furiously just as he did when he rammed his body, over and over, into the concrete until he bled and the guard came to see if he was still alive.
That is night for Moazzam Begg, a 43-year-old British Muslim. During the day, he seems confident. He speaks publicly and often about his experience as an "enemy combatant" at the U.S. military's Guantanamo Bay detention facility in Cuba. He spent three years there, two in solitary confinement, until British authorities negotiated his release in January 2005. He's been trying to get back to some kind of normal since.
Though the United States accused him of aiding the Taliban and al Qaeda, and a Defense Department official said this week that no changes have been made to his detention documents, Begg has not been charged or prosecuted. He claims he was wrongly detained, abused and tortured while in U.S. custody. He maintains that he's never had any ties to terrorism.
In 2010, Begg and eight other British ex-Guantanamo detainees won an out-of-court financial settlement with the UK government. The group accused British intelligence forces of complicity in abuse and torture while they were in U.S. custody.
'Gitmo will never close'
In the years between his release and that settlement, Begg has worked primarily as a public speaker, talking to large crowds about Guantanamo and working with international aid and human rights groups. He has been one of the most high-profile faces on Guantanamo, and leads a London-based group, Cageprisoners, which says it raises awareness about the cases of detainees.
"Things have gotten better over the years, certainly the way I am able to talk about it to a lot of people has improved, because I couldn't speak to anyone in the beginning, even my own family," he said. "And I still struggle personally, very much. It's not resolved in any way, how this has affected me and them. It's been five years, and I'm only beginning to work through how bad this experience was."
Begg expects he'll wake from some kind of Guantanamo nightmare Wednesday when the controversial prison, known as Gitmo, turns 10 years old. President Barack Obama pledged during his 2008 campaign that he would close Guantanamo, but the administration has struggled to find countries that will take its remaining 171 detainees, and Congress has blocked funding for that effort. See who is "too dangerous" to release.
"Gitmo will never close. That is a fantasy," Begg said in a phone interview from his home in London. "I've stopped wishing for it. Even if it closes its doors, it will be only symbolic. The detainees who are still there will go somewhere else to be held and be treated possibly worse, and still not get their time in court. And Gitmo, in a way, will always be open. It will be in my memory, in my head, just like everyone else who experienced that hell."
On January 11, 2002, Guantanamo's first 20 detainees were imprisoned. Over the decade, it came to hold 779 detainees representing 30 nationalities, according to the Defense Department. The majority have not been charged; 600 have been transferred to other countries, according to a joint New York Times and NPR investigation.
When it opened, the United States was just four months out from the September 11 terror attacks. This new kind of facility, on dozens of acres in Cuba, was meant to house what the Bush administration called "enemy combatants," a category of detainees who would not qualify for prisoner-of-war status under the Geneva Conventions.
'Our daughter ... saw everything'
Begg was picked up in Pakistan in 2001, accused of aiding the Taliban and held as an enemy combatant.
He said he was working in Afghanistan in the late 1990s and living there in 2001 to establish a school for girls. He and his pregnant wife and two children -- all living in Afghanistan doing aid work -- had relocated to Pakistan for safety during the U.S. invasion of Afghanistan in 2001, he said. The couple had planned to spend their lives doing aid work around the world.
On the night he was arrested, Begg said, men in plain clothes who seemed to be Pakistanis came to his home and banged on the door just after midnight.
He opened the door and they pushed inside, Begg recalled. He said the men put a hood over his head and carried him out to a waiting car. When he was placed in the back seat, his hood was removed. A man with an American accent put handcuffs on him, he said.
"These are from the widow whose husband died in the 9/11 attacks. She wanted you to have them," the man said, according to Begg.
Begg remembers his wife screaming and telling the men not to go into a back room where his two young children were.
"Our oldest -- our daughter who is now 16 -- she saw everything," he said. "Only now am I fully understanding how draining and emotional and difficult my being gone and what that night itself has been for her."
Begg has a high profile in the UK from speaking engagements and activism. He has written a memoir with the help of a Guardian newspaper editor, called ''Enemy Combatant: My Imprisonment at Guantánamo, Bagram and Kandahar." A movie has been made, inspired by his story. He has even consulted on a video game called "Rendition: Guantanamo."
"My daughter, really, has been the most affected," he said. "Her friends at school, of course, they ask her about this."
After he was taken from his house in Pakistan, Begg said, the men took him to another house in Pakistan. It was large and opulent with chandeliers and fancy tiled flooring. There he was interrogated for months.
"I was naïve about it. I thought they would let me go if I just explained to them that this was wrong," he said. "I am not as naïve anymore. That is one thing that has changed about me."
Begg said he was sent to Bagram Air Force Base in Kandahar, Afghanistan, where he witnessed the deaths of other detainees, which he believes resulted from their mistreatment by guards and interrogators.
He said he is still haunted by the sounds of a woman screaming near his cell at Bagram. He was convinced at the time that it was his wife.
It was not. She had not been detained. He would learn that when he returned to her more than three years later.
He hesitates to speak about their relationship.
"I just want to say that it has not been easy," he said. "It's not like I got a counselor when they flew me back to England. I had to deal with things by myself. So you do what you need to do to carry on."
'It's like you're free but not really'
Sometimes when he needs to think, or needs to calm his nerves, Begg retreats to a room alone. "I find myself pacing three steps forward and three steps back because in a cell at Guantanamo, you cannot do any more than that."
In the year after his release, Begg said he was gripped by debilitating fear when he had to travel by train in the UK. He was paranoid about being labeled a terrorist. He found himself thinking back on growing up in Birmingham, England, and getting into fights with white boys who taunted him by calling him "Paki."
"When I did eventually restart my train journeys it was with double the apprehension," he wrote in his memoir. "People might think of me as a terrorist because of how I looked, if I wasn't wearing the right sort of jacket, if I walked too fast or too slow."
"I was afraid of being shot," he wrote. "And I was afraid of being bombed."
Begg said he used to be a very shy person. Despite his law school training, he wasn't a skilled public speaker.
"I learned how to articulate myself through all those interrogations," he said, laughing. "Over 300 interrogations with the most powerful interrogators, people who will break you, it did something good for me. I have to thank the FBI, CIA and MI5 for that."
Travel has gotten easier psychologically, but not practically. Begg said he has traveled to Tunisia and Libya to meet revolutionaries who toppled their regimes, yet when he flew to Canada recently, he wasn't allowed to get off the plane. He said that officials would not allow him to enter the country because he had been a Guantanamo detainee, so he had to stay on the plane and fly back to England.
"There was some disgust," he said. "It's like you're free but not really. Then there are people who try to understand you, and that is very hopeful and encouraging."
While CNN.com interviewed Begg, he was at home tooling around on his Facebook page. He has 4,999 friends.
"While we were talking, a former Guantanamo guard has sent me a message," he said. "She just got my book and wants me to sign it for her.
"I've got loads of former Gitmo soldiers on my Facebook. I think it's a difficult relationship. She's still in the military, but she's very sympathetic to the campaigning I do."
Begg said he and his wife have had a former Guantanamo guard come to his home for dinner.
It also seems that at least some American officials may have changed their opinion of Begg. An American diplomat praised him in a January 2009 cable from Luxembourg after listening to the former detainee talk about Guantanamo after a screening of a film about torture.
WikiLeaks published that cable last year, in addition to 800 classified U.S. military documents about suspected al Qaeda operatives housed at the prison.
In a cable titled "To Hell and Back: Gitmo ex-detainee stumps in Luxembourg," the American ambassador to Luxembourg, Cynthia Stroum, said that Begg was "barnstorming throughout Europe pushing governments to accept GTMO (Guantanamo) detainees for resettlement."
"Mr. Begg is doing our work for us and his articulate, reasoned presentation makes for a convincing argument," she wrote. "It is ironic that after four years of imprisonment and alleged torture Moazzam Begg is delivering the same demarche to GOL (the government of Luxembourg) as we are: please consider accepting GTMO detainees for resettlement."