Giovanni Reyna's mother Danielle told U.S. Soccer how Gregg Berhalter kicked his wife in 1991 as she was angered by treatment of her son after the World Cup.
Berhalter revealed on Tuesday he was the subject of an investigation as he admitted to the altercation.
The United States head coach said U.S. Soccer was made aware of the incident by "an individual" who planned to "take me down" during the World Cup.
Danielle Reyna has now released a statement confirming she was the individual involved, explaining her frustration at criticism of Giovanni.
"I thought it was especially unfair that Gio, who had apologised for acting immaturely about his playing time, was still being dragged through the mud when Gregg had asked for and received forgiveness for doing something so much worse at the same age," she said.
Berhalter had seemingly referenced Giovanni Reyna when he detailed how one USMNT player was almost sent home from Qatar due to poor behaviour.
The player criticised the "highly fictionalised versions of events", having been forgiven, he said, for a lack of effort in training after learning of his "limited role" in Berhalter's plans.
Also on Wednesday, Claudio Reyna, Giovanni's father and Danielle's wife, as well as a former USMNT team-mate of Berhalter, confirmed he had been in contact with key U.S. Soccer personnel, although he denied threatening the coach.
"While in Qatar, I shared my frustrations about my son's World Cup experience with a number of close friends, [U.S. Soccer sporting director] Earnie [Stewart] and [general manager] Brian McBride among them," he said.
"However, at no time did I ever threaten anyone, nor would I ever do so."
Berhalter's U.S. Soccer contract expired last week, with assistant Anthony Hudson set to lead the team in their January friendlies.