The 39-year-old said her young son claimed he had been imprisoned in a bag and repeatedly punched during a conversation about a school project on bullying.
The primary school pupil later alleged he had been bound hand and foot with Sellotape by James Menzies. His mother said she had already warned Menzies that his “play fights” with her eldest child were too rough.
When the allegations of violence came to light in December 2010 she put Menzies’ belongings on the street and told him he was no longer welcome in her home, she said.
She told Livingston Sheriff Court she was working seven days a week at the time doing three jobs.
Giving evidence on the third day of a jury trial, she said the alleged assaults on her elder son, who is now 15, always started the same way.
She told the court: “There was what was called ‘play’ with my son which I had to stop on a number of occasions. It started gently, having fun, but got obviously more than fun.
“He [Menzies] was giving [my son] dead arms and dead legs, but to the extent that he was in tears. He would grab him, start doing the ‘typewriter’ – jagging your fingers in – then get into punches.
“Initially [my son] would be on his feet but then he was always on the ground with Jim kneeling on top of him. It began as fun, but some of the times it got to the stage where he was in tears with it because of the force behind the punches.”
She claimed she witnessed the accused repeating the alleged assaults “two or three times”. She described how she saw him pin her teenage son to the ground and repeatedly punch him on the arms and legs “five to ten times”.
Asked by prosecutor Brent Bissett what had made her intervene, she replied: “Seeing my son in tears.”
She added: “I said he shouldn’t be doing that. I said it might be fun to him but it obviously wasn’t fun for [my son] because he’s ending up in tears. He basically ‘humphed’ and walked away.”
Under cross examination by defence lawyer Hazel McGuinness, the mum denied telling her children to lie in court to get Menzies into trouble.
She said: “I don’t want to ruin his life. I’ve no reason to ruin his life.”
Menzies, 35, of East Whitburn, West Lothian, denies assaulting the primary pupil by placing Sellotape around his hands and feet, putting him in a bag, hanging the bag on the wall and repeatedly punching him on the body. He is also accused of locking the boy in his room.
He further denies assaulting the boy’s brother by pinning him to the ground with his legs on the youth’s body and repeatedly punching him on the body to his injury.
The trial continues.