In the video, only Luke's chair is visible.
But, in the background viewers heard what sound like a slap, followed by panicked scream from Ms Campbell and the couple's two children - aged three and two.
Ms Campbell said he played the game for much of their relationship, but the addiction only gripped him in the past year.
"He got famous and started playing six to eight hours a day for his fans," she told Daily Mail.
"As he got more addicted he changed, he became an angry person.
"He wasn't spending enough time with the kids and it was a struggle every day to get him to leave the computer for anything."
Ms Campbell revealed the alleged assault has left her receiving death threats from many of Munday's fans.
"They even said I was a bad mother and should lose my kids," she said.
Munday faced Camden Local Court on Dec. 13. where his assault charge and an AVO were adjourned until Jan. 10.
Munday earlier insisted the alleged assault was a one-off, as Ms Campbell also said, and that the livestream didn't tell the full story.
"You're all judging the video, you don't see what happens, you haven't read the police report, you don't actually know what happened off camera," he told The Daily Telegraph.
Munday has also been suspended from his role at Telstra.
In a statement, Telstra General Media Manager Steve Carey condemned the alleged domestic violence attack.
"This behaviour goes against what we stand for as an organisation and the work we have done to assist women impacted by domestic violence," Mr Carey said.
"We have suspended Luke's employment pending a full investigation and will co-operate with any police investigation.
"Domestic violence has no place in our community. It is totally unacceptable and needs to be eradicated."