The woman, who can't be named under a publication ban, spoke Thursday after David James Leblanc appeared in Nova Scotia Supreme Court in Bridgewater.
He entered guilty pleas to eight of 16 charges in two separate cases.
Leblanc originally faced seven charges in the case of the teen who was confined at a home in Upper Chelsea, including sexual assault, sexual assault causing bodily harm, forcible confinement, uttering a death threat, kidnapping, administering a noxious substance with intent to cause bodily harm, and breach of conditions.
He pleaded guilty to these five charges:
- Sexual assault.
- Forcible confinement.
- Uttering a death threat.
- Breach of conditions.
The other two charges were withdrawn.
The mother of the teen said being in the same courtroom as Leblanc was hard on her.
"That was the very first time that I've been in the same room with David Leblanc and I found it very difficult. Just uncontrollably shaking," she said.
"As a mother, I just wanted to just be alone with him. I just wanted him to suffer. Normally I'm not like that, but it was just overwhelming. I want him to suffer."
Leblanc also entered three guilty pleas in an unrelated child pornography case in which he took photos of two boys — aged five and two — and posted them online. He pleaded guilty to making child pornography, distributing child pornography and sexual interference.
Two other charges in the case were withdrawn.
- Key moments in the Nova Scotia chained-teen case
The Crown said it would recommend a sentence of 11 years — eight for the confined teen case, and three for the child pornography case — with credit for time served when Leblanc is sentenced on June 14.
"I hope he's in there for a really long time and I hope those inmates in that place get to him. I'm sorry, but there is no useful place for that man in society," said the teen's mother.
"I don't think he'll ever change. I think he's a sick person. He knows what he did is wrong. You can't not know that it was wrong, but he did it anyway."
Mike Taylor, Leblanc's lawyer, told CBC News earlier that his client would plead guilty because he wants to "accept his responsibility and move on."
"He's certainly got a lot of evidence against him; he knows that he's committed these offences," said Taylor. "He doesn't want to put anyone else through any more formalities than he's already done."
Leblanc wasn't the only one accused of chaining up the teenager in an isolated house in Upper Chelsea.
His co-accused, Wayne Alan Cunningham, died while the two were the focus of a countrywide manhunt that began when the teen escaped from the home and showed up on a doorstep, barefoot with chains around his wrists and ankles.
At the time, RCMP said they believed the 16-year-old was held captive for 10 to 14 days before he was able to escape.
The teen's mother said her son kept his wits about him during his horrifying ordeal.
"When he was still in captivity, he was leaving evidence all over the place. He was making and taking mental notes all the time because he knew that he was going to get out and he wanted the proof that he was there to be indisputable," she told reporters outside the courtroom on Thursday.
"He's coming to grips, and trying to live a normal life and to put it past him. He just wants to move on, I think, and just forget about this whole ordeal, as difficult as it is. It's just going to take time."
The details of the case shocked people across the country.
Leblanc was discovered in northern Ontario not far from Cunningham's body. Police said there was no foul play in Cunningham's death.
A third man, John Leonard MacKean, 63, of Halifax was later charged in connection with the case. His accusations include sexual assault and communicating for the purposes of obtaining sexual services from a person under 18.
He has elected trial by judge and jury in Nova Scotia Supreme Court. A preliminary hearing is scheduled for July 25 in Bridgewater.