It was only later, after the intense shock had subsided and a heavy pain was starting to bed in, that Robi Damelin was told what her first words were on hearing that her son had been killed: "You may not kill anybody in the name of my child." She says now: "I suppose that was some kind of prediction of what I would do in the future. But I don't know what revenge means. How many people should I kill? Would that bring David back? I was very motivated to find something that would prevent other families experiencing this pain."

In 2002, David, a university student who had been doing his reserve duty in the Israeli Defence Force, was killed by a Palestinian sniper while he was guarding a checkpoint. Damelin, who was running a PR agency in Tel Aviv, could no longer work – it felt meaningless. A group called the Parents Circle Families Forum asked if she would like to join them: set up in 1995 by Yitzhak Frankenthal, whose 19-year-old son was killed by Hamas fighters, it now comprises more than 600 bereaved Israeli and Palestinian families working together to campaign for reconciliation.

"It was quite extraordinary to meet Palestinian mothers and discover this joint pain, and how powerful we could be as a force together to make a difference," she says. "And so I got swept along, and it became more and more my life. And now, apart from my grandchildren, there is nothing else – I have become a very one-dimensional character, absolutely geared to this idea. This latest Gaza mess is just so indicative of the cycle of violence. It's not working for either side. Neither of us can win this battle. All that will happen is there will be more and more broken hearts."

We meet a few hours before the ceasefire ended eight days of violence in Gaza. The issue, says Damelin, is how long it will be until the violence flares up again and another short-term ceasefire has to be negotiated. "Sometimes I can't believe the stupidity of the repetition," she says. It doesn't threaten the unity of the group "because we don't allow this situation to affect who we are.

"We continue to work. The Palestinians from our group continue to come to schools and talk. I'm not sure if I watched the news on Al Jazeera every day I would continue to come and talk about reconciliation, so we think that's a really good indication of the trust within this organisation."