Just after Ben Roberts-Smith's former wife had met the decorated soldier's mistress he threatened her to lie about the affair or lose her children, she has testified.
Emma Roberts also told the Federal Court on Monday she uncovered USBs stashed in a pink lunchbox and buried in her garden by the decorated soldier.
Ms Roberts - who married the special forces soldier in 2003 - said her life "imploded right in front of me" when her husband's girlfriend turned up at her doorstep unannounced in April 2018.
She had earlier received an anonymous letter detailing various secret hotels and witnessed strange behaviour including him continually taking "selfies" not for her, she said.
But Mr Roberts-Smith continued denying the affair until the woman codenamed Person 17 appeared at her Sunshine Coast home "crying a lot".
Person 17 revealed a pregnancy with Mr Roberts-Smith's baby, and showed her hours of text messages together, Ms Roberts said.
"It was very clear they were having an affair, they were planning to be together," she told the court.
"I asked why she was not seeing him (anymore). She kept pointing to her black eye and she said 'because of this'."
The Victoria Cross recipient is suing The Age, The Sydney Morning Herald and The Canberra Times for defamation and denies their reports that he committed war crimes and murders in Afghanistan between 2006 and 2012.
Mr Roberts-Smith has strenuously denied all wrongdoing including allegations he assaulted the woman.
He told his wife if the allegations ever surfaced in the press "that I was to lie," she said.
She didn't want to lie, she said, but then he pointed to the couple's children, saying: "If you don't lie, you will lose them."
"I knew at that point I had to lie for him."
After a newspaper article detailed the affair, Mr Roberts-Smith organised a front-page story in The Australian and Ms Roberts was told to "look sad" for their photograph together.
"I said 'I didn't want to do it' ... I said 'I'm not speaking to the media'."
Later she got wind of authorities becoming "very interested in what Ben was doing in Afghanistan".
Nearing their separation in January 2020, Ms Roberts became suspicious he was withdrawing cash from their joint bank accounts and "stashing it" in their garden.
She described the "very obvious" location hidden underneath a rock and a hose reel where she and her best friend Danielle Scott together dug 30cm underground.
Buried in the soil she found a box containing several USBs in duffle bags, which she gave to her friend who downloaded them onto a laptop.
"I said 'I do not want to see what's on them'," she said, before returning the box in the ground.
Later she distinctly recalls Mr Roberts-Smith leaving "sweat drops" around the home when he came to collect the package.
His barrister Bruce McClintock SC accused Ms Roberts of fabricating the entire story, asking why there was no photographic evidence of the package.
She denied this, and dismissed suggestions she loathed and detested Mr Roberts-Smith,
Mr McClintock then read out a number of her text messages in the month they split.
"I'm actually feeling so f***ing angry today," one read.
"I want to punch the f***ing c*** in the face," read another.
"That's how you saw my client?" he asked.
"Nine days after he left, yes," she said.
Ms Roberts said her then-husband spoke of another SAS soldier having his house raided thanks to a tip-off he gave the Australian Federal Police, saying it would "scare the others".
After she read a news article of letters being sent, she asked him "what the f*** have you done?"
She said he had become "paranoid", and admitted writing letters and handing them to someone else who posted them across the state border in NSW.
The trial continues.
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