Former British Prime Minister David Cameron on Saturday spoke out on Brexit, saying he was "truly sorry," and criticized Prime Minister Boris Johnson's leadership before the release of his personal memoir, "For The Record." 

"I am truly sorry to have seen this country I love so much suffer uncertainty and division in the years since then," Cameron said about the U.K.'s political situation since voting to leave the EU in June 2016. 

Cameron also criticized Johnson for suspending U.K. parliament and expelling members of the Conservative Party for disagreeing with him. Speaking with the London Times, Cameron said Johnson and MP Michael Gove behaved "appallingly" during the referendum campaign.

Brexit was a political gamble for Cameron, who sought to appease Eurosceptic members of his Conservative Party by holding a referendum to leave the EU, although he personally opposed the idea. His strategy backfired, forcing him to step down shortly after the referendum. 

"Every single day I think about it, the referendum and the fact that we lost and the consequences and the things that could have been differently, and I worry desperately worry about what is going to happen next," Cameron said.

Cameron's move has made him unpopular with both sides of the Brexit debate, as pro-EU Brits oppose him for launching the referendum and Eurosceptic Brits disagree with his campaign to remain in the EU. 

Cameron's autobiography, which hits stores next week, could be a flop, due to his unpopularity and a low number of preorders. Some U.K. bookstores that oppose Brexit have chosen to not stock the memoir. 

The book will not only contain his thoughts on Brexit, but also on hot-button issues such as his decision to support gay marriage and his government's use of austerity in the wake of the European economic crisis of 2008.