“He’s thrown three weddings for goodness sake. Who needs three weddings in a year, give us a break,” Cass told a reporter at Sydney's airport.
“Three weddings and a funeral. We had a funeral and it was my dad’s.”
Cass went on to claim her ex had “a lot to hide”.
“I’ve done a lot of reading about narcissism,” she added.
“Everything he says is about this fake person who lives in this fake castle, it’s not real,” Cass continued.
“Does the country really believe he wore the same suit every day for a year?" Cass asked, appearing to refer to a 2014 "experiment" Karl conducted on the Today show in a bid to make a point about sexism.
"Women are judged much more harshly and keenly for what they do, what they say and what they wear," Karl told Fairfax at the time.
"I've worn the same suit on air for a year – except for a couple of times because of circumstance – to make a point."
Cass appeared to take issue with her ex-husband's claim.
"Did anyone go and check every tape of every day?" she asked. "No. They just believed it because he said it. And one saying is that if I say it it’s true and that’s what he thinks.”
Cass added: “After we separated he... said [to me]: “It is very, very hard to be the best journalist in Australia, quite possibly the world”. That tells you who that man is and who he thinks he is.”
Cass also said she didn’t have a PR team “but I also don’t need one”.
“What do I need to promote? Myself as a mother? My children know how good a mother I am.
“They know they are the most important thing to me and I am the most important thing to them.
“They know that and I don’t need to prove it to anyone. And you know what? I think people know this.”