The former couple were due to marry in the NSW Southern Highlands in November 2016, but they split three months before the wedding was due to take place, Bergin previously told news.com.au.
He has refused to comment on how the relationship ended, saying: "I'm just a spectator in this like everybody else."
He also denied online reports Campion had refused to return the ring.
"It seems that some people feel like they can just make things up," he said.
Joyce stepped down from his role as Deputy Prime Minister under party pressure from the relationship that led to questions over his expenses and conduct while the pair worked together.
He then appeared to cast doubt on the child's paternity in a recent interview, saying it was a "bit of a grey area".
"It's mine. On the record, there it is. And can I say, even if it wasn't, I wouldn't care, I'd still go through this, I'd still love him," he said, adding that he had no intention of getting a DNA test.
He also slammed the Daily Telegraph for splashing with a picture of Ms Campion on the front page while heavily pregnant with the headline "Bundle of Joyce."
"How could they know? "They never even asked if it was 'Joyce's bundle'," Joyce said.
The Daily Telegraph said repeated questions put to his representatives went unanswered.
On Monday, he said questions about the baby are "nobody's business" but his and Campion's.
"Anything that's personal in nature is nobody else's business but mine and Vikki's, nobody else's business. So we're not here to be part of some ongoing litany of discussions about this," he said.
