"He definitely thinks about it and he can't erase it", she said of her son, who is now 19.
A former production assistant who worked on the show in its early seasons detailed an incident where he picked up Spacey and drove for him.
A restaurant worker saw this incident and told that boy to escape when Spacey had gone to use the bathroom.
Unruh explained that her son was left "star struck" and "frozen" by what had happened. She told him to run, and he did.
On the bystander's advice the teenager fled to his grandmother's home, where he and his sister called their mother.
Unruh said her son told Spacey that he was of the legal drinking age. "Right now my son is anxious, but he's also confident that the time to act is now". "He did not report the crime at the time, and that was largely because of embarrassment and fear".
Unruh is planning to hold a news conference with attorney Mitchell Garabedian in Boston at 11.30am to discuss her claims. Garabedian said he is conducting his own investigation. "And one way to stop it is for courageous victims and their families to speak out so that children are safe, other victims are empowered and the victims themselves are emboldened".
The Independent was unable to reach a spokesman for Mr Spacey, whose former public relations representative recently severed ties. Her son has filed a report against Spacey.
Assistant Cape and Islands District Attorney Tara L. Miltimore confirmed to the Herald that Spacey, 58, is under criminal investigation.
Famed author and journalist Gay Talese has a message for all the alleged victims of actor Kevin Spacey's sexual misconduct: "Suck it up".
The writer also compared Spacey to the Dalai Lama, who likely "has done something he's ashamed of".
"I would like to talk to Kevin Spacey", [Talese] said.
Unruh's story comes amid multiple allegations that the actor has made unwanted sexual advances toward young men over the years. London police are reportedly investigating Spacey for a 2008 sexual assault. She paid particular attention to the allegations against Spacey and sent two tweets in mid- and late October that explained why.
"The #weinsteinscandal has emboldened me- #truth time", she tweeted.
Spacey has said he was "beyond horrified" by Rapp's previous claim of assault. Time the dominoes fell'.
Since Rapp made his allegations, Spacey has been hit by at least 10 other claims.
"I applaud your courage Actor Anthony Rapp @albinokid. And shame on you for using your apology to Anthony Rapp to come out as a gay man", Unruh angrily said.
The two-time Emmy victor has not been arrested or charged with any crime.
Since then, other allegations have surfaced and the Oscar-winning star said he is seeking "evaluation and treatment".