The father of a schoolboy targeted by a former Marlborough teacher who today admitted sexually abusing teens says her actions were "disgusting".

And while he is relieved she has admitted the offending, sparing his son the pain of testifying at a trial, he is worried she will not face serious consequences.

The woman today pleaded guilty to having sex with two 15-year-old boys in parked cars, often telling the victims she loved them and them explicit videos.

She engaged in group sex with the victims, having sex in cars with tinted windows parked in public places.

The 37-year-old woman, who was a high school teacher at the time of the offending, has been granted continued name suppression.

She appeared in Blenheim District Court today and pleaded guilty to seven charges of unlawful sexual connection with minors, and one of exposing a minor to indecent material over a year-long period.

The father of one boy had no idea about the guilty plea until he got a notification on his phone from a news media app.

He said he was pleased she was taking responsibility for her offending.

"She is a predatory maggot," he said.

"It's pretty disgusting."

He said the offending against his son fell at the lighter end of the woman's raft of charges but was still "pretty yucky".

"She's the adult, she should have known better.

"It's nasty."

He was angry she had name suppression and hoped that would lift at sentencing.

The fact she was on bail was also infuriating, he said.

"Even being on bail... that allowed her to walk around town like a f**king rooster.

"My son is involved in sport and she's been in places where he's been, walking around like nothing was going on which made him pretty uncomfortable.

"Considering she was supposed to be staying away from these kids... it's pretty disgusting."

The Herald revealed complaints had been made to the police after the woman made appearances at a local sports venue and a school assembly.

Her bail conditions specified she was not to have any contact with anyone under 16 apart from members of her own family.

Police looked into both complaints said that after "reviewing the circumstances" no further action would be taken.

The victim's father hoped the woman would receive a sentence that reflected the seriousness of her offending rather than "just a Chinese burn".

"It's sickening," he said.

"Ultimately, she is a person in a position of power and responsibility and she just totally abused that in every way she could."

He said his son was trying to focus on exams and he was glad that the boy would not have the weight of a trial on his mind.

"Life will just go on," his father told the Herald.

"Let's just go on from here and forget about this bad stuff."