I t was an event that could easily have passed in an emotional blur: the moment Clemantine Wamariya was reunited with the family she’d last seen 12 years earlier, and had for a long time feared were dead. Instead, she can recall every second: the moment she threw herself into her father’s arms, before clinging to her mother and, in a gesture of disbelief and gratitude, raising an arm to the heavens.

The reason everything is still so clear 12 years on is because the reunion took place on television, and she has rewatched it many times. “I thought in that moment I’d died,” Clemantine says. “You hear about how you’re united with the people you love in heaven, and I thought, this must be heaven. I was so happy, but I was also scared: had I died?”

It was 2006, and Clemantine and her sister, Claire, thought they were being invited to appear on the Oprah Winfrey show to discuss their experiences of the Rwandan genocide. But, unbeknown to the sisters, the show’s producers had flown their family in from Africa. The last time they had seen their parents was in 1994, but although they knew they were alive, they had been able to speak only by phone and had no idea when they would be able to meet; they had also missed the birth of a new brother and sister, then aged eight and five.

They’d had, Clemantine says, an idyllic childhood, growing up in the Rwandan capital, Kigali: her father ran a taxi business and her mother’s life centred on the family garden, where they grew mangoes, lemons and papayas alongside hibiscus, geraniums and peonies. The family were Tutsis, although that didn’t seem significant until the slaughter began.

For Clemantine, the first sign of trouble was when her parents started to talk in whispers. Neighbours were disappearing, and there were loud, ugly sounds in the air that her brother Pudi said were thunder (Pudi survived the genocide, but died of meningitis before the reunion). One day, her mother told Clemantine, then six, and Claire, 15, to pack because she was sending them to their grandmother’s farm a few hours south. Her parents had hoped they’d be safe there, but a few days later there was a knock at the door and her grandmother told the girls to run. They ran; her grandmother, cousins, aunts and uncles were killed.

The only thing Clemantine managed to take with her was a rainbow towel. “I held on to it. Claire and I lived on fruit. Days were for hiding, nights were for walking. Suddenly, we were refugees.”

They remained refugees for the next six years, wandering through seven African countries. Clemantine’s book, published this week, details the highs and lows of that extraordinary journey: the refugee camps, foraging for food, the illnesses and unexpected kindnesses that taught them how to hold on to hope. Finally, when Clemantine was 12, she and Claire were given asylum in the US – She went to live with a family in Chicago and Claire, who by then had children of her own, lived nearby.

In those early years in the US, Claire had a cleaning job, and Clemantine often helped her out. “We didn’t have a TV, but we discovered Oprah by watching it where we were working. We’d always make sure we were cleaning the sitting room at 4pm so we could catch her show. Claire used to say, ‘We’ll meet her one day, I just know we will.’”

Clemantine entered a high school essay-writing competition, organised by Oprah’s show, about Night, Elie Wiesel’s book about the Holocaust, and why it was still relevant. She wrote about her experiences in Rwanda, which led her to Oprah. When the sisters were invited on, they could hardly contain their excitement. “They put us up in a hotel, and we thought, ‘This is insane: we’re going to meet Oprah!’ We spent hours getting ready.”

Clemantine and Claire were in the audience when, midway through the recording, Oprah spoke to them from the stage. She asked Clemantine how long it had been since she and Claire had seen their parents, then she held up an envelope and said she had a letter from them. “She called us on to the stage,” Clemantine says. “Claire was holding on to me, she was shaking. Oprah handed me the letter and I began to open it, but then Oprah put her hand on mine. She said: ‘You don’t have to read it right now, in front of all these people, because… your family is here! We have flown your family here.’”

Clemantine couldn’t believe what she was hearing. “I’d been praying and hoping for so long that I’d see my family – it was the constant thought in my mind. I remember when we were in South Africa, there was a man who looked exactly like my dad and I used to wait for him on the street when I knew he’d be passing, just so I could see him.”

Now, with no warning , she was being swept up into her father’s arms, hugging her mother, cuddling her siblings. “Everyone was crying: everyone in the audience, all the crew. Everywhere you looked, there was someone with tears running down their face. They had to have a 30-minute break, just to give people time to recover, before they went back to recording the show.”

In her book, Clemantine recalls how, after the show, the family were driven by limo across the city to Claire’s apartment. “Nobody talked in the car. In the apartment, nobody knew what to do, either. My mother, in her long blue dress, kept sitting down and standing up and touching everything. My father kept smiling, as if someone he mistrusted was taking pictures of him. Claire remained nearly catatonic: rocking, stone-faced.”

Over the next couple of days, they went sightseeing in the botanic garden and for a ride on a ferris wheel, and then, on Monday morning, Clemantine’s parents and her siblings flew back to Rwanda. Clemantine went back to school.

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Today, Clemantine’s family have all moved to the US. They live in Chicago, and she lives in San Francisco. Now 30, she works as a human rights advocate. But the years of separation, she says, have left deep scars. “Claire and I are different people, and it’s hard to connect with our parents, because so much was taken away from us. When we’re together, we don’t really know where to begin; it’s difficult even to have a conversation.” She devoted her studies to researching the effects of family separation; she’s fascinated, she says, by how people are affected by loss, and what can and can’t be recovered after a family is ruptured.

For her part, Oprah described the onscreen reunion as “one of the deepest, most joyful moments I’ve ever experienced”, calling it “beautiful… raw, raw, raw… pure”. What, though, does Clemantine make of it, 12 years later: was it right, or fair, that she and Claire were put through such a pivotal, emotional experience with no warning, and in front of millions? “You know, when people watch that clip they always feel something. Some feel joy, some feel sadness, some feel confusion, some feel anger. But for everyone it’s a trigger-point for something, and what I think it does, more than anything, is underline the power of our stories and the power of sharing our stories. Everywhere I go in the world, people have watched that moment and know what happened. I met someone from Australia who told me that clip had changed her life. So whatever anyone feels about it, it’s testament to the power of the human story and the power of reunion. I feel happy about that.”

• The Girl Who Smiled Beads: A Story Of War And What Comes After, by Clemantine Wamariya and Elizabeth Weil, is published by Hutchinson at £16.99. To order a copy for £14.99, go to guardianbookshop.com or call 0330 333 6846.

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