Brendan Cox told how shock had given way to grief following the vicious killing, but he had been comforted by the nationwide "wave of compassion and kindness".
As thousands of people prepare to take part in events honouring his late wife, Mr Cox said bringing communities together was "more important now than ever".
"When Jo was killed a year ago it took the heart out of our family," he said.
"The first emotion was shock, both numbing and shattering. That in time gave way to a grief that remains very fresh, very raw and continues to hit us in vicious waves when we least expect it. But our family has not been broken."
Mother-of-two Mrs Cox was shot and stabbed on June 16 last year as she arrived for a constituency surgery in Birstall, West Yorkshire. She had been elected as Labour MP for the Batley and Spen constituency just 13 months earlier.
Right-wing loner Thomas Mair was given a whole life term after being convicted of her murder at the Old Bailey in November.
Mr Cox said his wife's killing "aimed to divide communities but has instead brought them together".
He added: "Her killing by a far-right extremist shocked the country and unleashed a wave of compassion and kindness that has comforted us ever since and for which we are extremely grateful.
"At a time when extremists of all types are trying to divide our communities there is a huge ground swell of people who just want to focus on the things that unite us, who want to draw closer to their neighbours and communities.
"I think people are sick of the narrative of hatred and division that neither represents who they are nor our great country."
Mr Cox said he was "awed by the scale of the reaction" to The Great Together, with more than 110,000 events honouring his late wife expected to be held from Friday to Sunday.
He added: "We hope these events give us all a moment - as Jo talked about in her maiden speech - to focus on the things we have in common.
"I also hope they are fun, full of energy and laughter. That's what Jo would have wanted."