Mr Joyce, who has since renounced his New Zealand citizenship, comfortably won the New England by-election on December 2, and resumed his cabinet posts the same day.
"Private matters remain private", Joyce told ABC's 7.30.
It's triggered a debate about whether the image and accompanying article amounted to an invasion of privacy, or was a matter of public interest. "People can not possibly know what people's personal circumstances are and certainly I, and I would hope no one on my side of politics is going to participate in a public debate..."
"One of the greatest failures of my life was the end of my marriage, and I do not in any way stand away from that".
"The situation for myself and the girls will be made worse by the fact that this will all be played out in public", The Australian reported Mrs Joyce as saying.
"[They are not thinking] "I wish the Daily Telegraph had suppressed the information that the Deputy Prime Minister had left his wife and four daughters for his former staff member almost 20 years his junior". It just means on that instance, as I said, I failed.
Campion, a former journalist, left Barnaby Joyce's office in April to work for one of his close Nationals colleagues, the resources and northern Australia minister Matt Canavan. "I can't quite fathom why basically a pregnant lady walking across the road deserves a front page".
"This situation is devastating on many fronts", Natalie Joyce said. "I'll be upfront I failed on that one, but I am not going to say therefore just because I failed I'm going to completely change my views and definition".
"Our family life has had to be shared during Barnaby's political career and it was with trust that we let campaign and office staff into our homes and into our lives", she said.More news: Gunmen kill officers, free militant in Kashmir hospital raid
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Natalie Joyce said she felt "deceived" by the news that Vikki Campion, 33, is pregnant with her husband's fifth child and claimed the extramarital fling began when she was a paid staffer.
Mr Joyce's family was noticeably absent during events previous year.
But others are questioning whether Joyce, a devoted Catholic, has been hypocritical in his opposition to allowing same-sex couples to marry while also carrying on an affair.
Rumours also plagued Joyce on the streets of his New England electorate during the byelection campaign he fought and won past year following his disqualification over dual citizenship.
A friend of the Deputy Prime Minister said the pregnancy was shrouded in secrecy because he was concerned about the well-being of his daughters.
The Department of Finance's disclosure log reveals journalists past year were trying to glean information out of Barnaby Joyce's comcar records.
"My heart goes out to the wife and daughters", he told Sky News.
"Once we start going through this salami slicing of a private life, where does it end?" he added.