For many of Europe’s imprisoned Jews, it would be easy to read the events of this day, May 16, in 1943, as an end of hope. It was then that the Warsaw Ghetto Uprising, one of the most significant acts of resistance during the Holocaust, was quashed.

But one woman who lived through it sees things differently. Survival, she says, depended on finding some tiny source of hope and holding on.

“When you are drowning and you see a straw, you hang onto the straw,” Sonia Klein, now 91 and living in Brooklyn, N.Y., tells TIME. “Is the straw going to save you? No, but the touch of hope may.”

Klein grew up as part of the thriving Jewish community in the city of Warsaw — a community that was, before the Holocaust, as TIME would later point out, the world’s biggest outside New York. About a third of the city’s 1.3 million residents were Jewish. In October of 1940, with Nazi forces occupying the city, those hundreds of thousands of people were confined to a ghetto of only a little more than a square mile. As Klein tells it now, they were promised that if they reported to certain areas of the city they would find work and food. They were starving already, so they did.

Because her uncle already had a building in the ghetto, she and her parents and siblings were able to get a room — but for an area of that size to absorb so many new residents essentially overnight was impossible. Most people were left on the street. “People were starving and it was winter and people were dying. Every morning that you were able to go out, you saw corpses,” she says. “Not even covered with newspapers, because there wasn’t enough time to do it, this is how many people were gone. How can one forget this?”

Read more: Color Photos From Nazi-Occupied Poland

Around the end of 1942, Klein says, word began to spread that the people who had been deported from the ghetto, supposedly to labor camps, were in fact being killed. Her father and a few other men used their hands to dig a hiding spot under the basement of a building, hoping that their families could survive inside for at least a year. By early 1943, they were underground. Each day, one person could go out to bring back food, using a designated knock to get back inside.

It was from there, in hiding but with radios informing them about the outside world, that they heard what was going on above ground: an uprising.

As the uprising continued over the next several weeks, one of Klein’s compatriots went out for food and was followed back to the hiding space. The secret knock came and when the residents looked up, they saw the telltale boots of the Nazis there to take them away. Coming to the surface for the first time since she had gone into hiding, she saw that while they were underground the ghetto had been destroyed. As TIME would later describe it, in the wake of the first wave of resistance, “[the] Germans brought re-enforcements from Galicia; waves of bombers swept over the defenseless ghetto, raining incendiaries and high explosive. It took them 42 days to level every building.”

“At this point we had two choices,” Klein says. “One was to remain there, and the ghetto was in flames already. The houses were burning in the ghetto. Life is a very precious thing and we said, well, either we go or we burn right here. We went out.”

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Klein and the dozens of people she’d been in hiding with were taken to Majdanek. For the act of not letting go of her young son’s hand, Klein’s mother was killed. Her brother, too. Her father (who would die soon after) was separated from Klein and her sister, who a few weeks later were transported to Auschwitz-Birkenau.

Klein believes that, due to the fact that it was the end of April when she was found, she must have been on one of the last transports out of the ghetto. Soon after, the uprising ended. Nazi forces deported about 42,000 Jews — almost everyone who remained, after thousands more had been killed during the uprising, compared to a dozen Germans killed during the initial fighting — to concentration camps or labor camps, according to the U.S. Holocaust Memorial Museum.

When the war in Europe ended almost exactly two years later, Klein and her sister had been on a months-long death march after having been shipped from camp to camp as the Allies closed in. All along, she says, she kept her spark of hope alive by promising herself that she would not be silent if she survived.

Klein met her husband just after the camps were freed and she says he started telling people what he had been through “since the day he was liberated.” But she found that talking about what she had seen was like reliving it, and she kept it mostly inside. All the while, she made a new life in the United States, first in Buffalo, N.Y., and then in New York City after her husband’s death; she and her sister still live near one another. About five years ago, Klein decided that her story was too important not to share. Silence, she says, means it could happen again.

One of the ways she does so is through a program called Witness Theater, which pairs Holocaust survivors with high-school students for a yearlong program during which the students, meeting regularly with the survivors and therapists and drama teachers, write a play to tell the survivors’ stories. “What the kids talk about is that they take on the obligation,” says Greg Schneider, executive vice president of the Claims Conference, which supports the initiative. “It’s passing on this obligation to a new generation who then become the witnesses.”

Other people cannot truly comprehend what she went through, Klein says, but at least they listen. Not that telling the story has gotten any easier over the years.

“I sit here calm and collected,” Klein says. “Do you think I’m going to sleep tonight? No. But that’s a small price to pay for what we owe our loved ones.”

Write to Lily Rothman at lily.rothman@time.com.