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Last June, Brendan Cox was at a restaurant with a colleague when he received a life-changing phone call. His wife, British lawmaker Jo Cox, had been attacked.

“I remember running to the train just thinking, just be OK, like if you’re injured, if you’re hurt, we’ll be OK, we’ll put you all back together, just don’t die. Then I was on the train and spoke to her sister, Kim, who told me that she hadn’t made it,” Cox recalls.

Jo Cox, 41, was shot and stabbed to death on a street in Birstall, northern England, following a meeting with some of her constituents on June 16 last year. The attack, which happened just days before the Brexit referendum, shocked Britain.

In the days after her brutal murder, with the encouragement of family and strangers, Brendan began to write. His tribute to the life and career of his wife – a young Labour Party MP heralded as a champion for women, immigrants and the vulnerable – helped him “process what has happened.”

Brendan Cox’s book, “Jo Cox: More in Common,” was released on the anniversary of Jo’s brutal murder this month. The title serves as a poignant reference to his wife’s maiden speech in Parliament, when she spoke of how British communities – including the one she represented – had been greatly enhanced by diversity.

Speaking to CNN’s Christiane Amanpour this week, Cox said he wrote the book for those “who wanted to learn more about her – people who felt she stood for something.”

“Her sense of our country and the time that we’re living in, where I think we spend a lot of time talking about diversity and difference and we’re not very good actually at talking about the things that bind us together,” Cox said.

He also spoke of a more personal bond he shares with his young children who, he says, carry “Jo’s spirit.”

In the book, Cox writes about one of the toughest decisions he ever had to make: whether to let the children see their mother one last time at the morgue.

“Seeing Jo’s body was an important part of them understanding and grieving,” Cox told CNN. “When you’re that little, death is quite a hard thing to conceive of and conceptualize. You have to be quite brutal, brutally honest so that they do understand what has happened.

“I think seeing their mom, and clearly knowing that life wasn’t there anymore, helped them move to that next stage,” he said.

Cox also tells of his surprise when then-US President Barack Obama called just days after Jo’s death, to offer his sympathy, and to invite him and the children to the White House. Before she became an MP, Jo had volunteered on Obama’s election campaign.

Now Cox has channeled Jo’s ethos and dedication to public service by organizing a movement he’s called “The Great Get Together” to share her “More in Common” philosophy.

Across the UK this weekend, hundreds of community events have been planned for Britons to “share food with their neighbors, and to celebrate the things that bind us together.”

The get together, supported by politicians and celebrities including chef Jamie Oliver, aims to bring cheer to a country that has suffered a string of terror attacks, a brutal election campaign and, most recently, a catastrophic fire in a housing estate in West London.

“We need even more so after Manchester (terror attack) and after London (terror attack) and after the election, after the referendum, just to say, let’s talk about those things that we have in common. I think it’s overdue,” Cox said.

CNN’s Kara Fox contributed to this report.