The former special forces soldier admitted he's not proud of all he did in Afghanistan but told a Federal Court judge the effect of the 2018 articles meant he struggles to get out of bed and is wracked with anxiety.

"I have had moments in my life where I just didn't think it would be worth it," he said of his three-year defamation claim.

But respect for his Victoria Cross and "what it stands for" - together with appreciation for the Australian Defence Force, former colleagues, family and his children - "keeps me going to set the record straight", he said.

Mr Roberts-Smith is suing the publishers of the Sydney Morning Herald, the Age and the Canberra Times over a series of articles he says defamed him by portraying him as a war criminal and a murderer.

The publishers say the allegations in the June 2018 articles are true.

Another article Mr Roberts-Smith says defamed him - concerning an allegation he hit a woman in a Canberra hotel room - is substantially true, the media companies say.

On the seventh day of the high-stakes trial, Mr Roberts-Smith, 42, admitted using prepaid phones sourced through a third party to call former colleagues in his quest to find the source of the first set of articles.

But he denied his motive was to avoid detection by military or police investigators.

He simply did not trust the media and their sources were not trying to intercept his communications, he said.

"The News of the World (phone hacking) thing was playing heavily on my mind," the Perth-born man said.

"My view was that I just needed to talk on something that wasn't going to be compromised."

The calls helped the former soldier patch together the 2009 and 2012 missions subject of the articles, including who was where when and what they did - because most of what had been written "was wrong and false".

He was in no doubt he was the special forces soldier dubbed "Leonidas" and says others cottoned on too.

Fielding calls on his personal phone from former federal police commissioner Mick Keelty and then-director of the Australian War Memorial, Brendan Nelson, he said the latter man was "disgusted with what had been written...about me".

Mr Roberts-Smith had done "everything I was supposed to do" in Afghanistan, even when that meant not intervening when faced with locals abusing women and children.

"I saw things ... and did things, like having to engage with adolescents, that I'm not proud of and I live with that," the 42-year-old said.

But coming home to "demonstrably false" articles that were based on others' lies and smears left him "traumatised", his family life "untenable" and his private business in ruins.

Mr Roberts-Smith said he was made to be a "deplorable human being" in the August 2018 article about the hotel room - the first to name him.

"I had so much anxiety and was so unable to engage with people publicly and, now having been named, I actually started thinking my life was over," he said.

Addressing an allegation in a recent 60 Minutes program, Mr Roberts-Smith denied burying a Tupperware container of USBs, saying it remained in his home office desk drawer until he retrieved possessions from the matrimonial home following his marriage breakdown in January 2020.

The USBs containing footage and images from several special forces tours had been sent to him "randomly" and anonymously through the post, he said.

"Probably naively" he didn't think pictures of a prosthetic leg and parties on base were an issue as "it had already been exposed", he said.

The media companies are due to begin cross-examining the former soldier on Thursday.

Australian Associated Press