Sonia Ruth Mackay, 43, faced the District Court today after pleading guilty to the persistent sexual exploitation of a 17-year-old boy.

In sentencing, Judge Liesl Chapman said Mackay had struck up a sexual relationship with a student in her year 12 English class.

Over the course of a month, the pair engaged in sexual activity “many times” at Mackay’s house, in her car, at the victim’s house and in public areas around Adelaide.

They drank alcohol and smoked cigarettes and cannabis together, and Mackay bought the boy presents and a nose piercing.

The boy said in a victim impact statement last month that Mackay also branded his flesh with a cigarette, and that the relationship caused him to withdraw from family and friends.

His mother said her son stopped coming home for days at a time and, when he did come home, Mackay called him and threatened self-harm.

The boy’s parents became suspicious and approached the school principal, who reported the matter to police.

When confronted by his mother, he admitted the sexual relationship and said he was in love with Mackay.

Judge Chapman said Mackay, whose marriage had recently broken down, was overwhelmed by grief, sadness and confusion at the time.

But she said the crime had breached the trust of the victim, his family, her employer and the school community.

“Your behaviour was manipulative and unforgivable,” she told Mackay.

“You seem to have lost touch with reality and were living in some sort of fantasy land.

“In light of what you were doing and the way you were doing it, it is evident to me that you could not have been thinking straight.”

Mackay and several supporters cried as Judge Chapman jailed her for four years, fives months with a non-parole period of two years, one month.

Mackay, a mother of two young children, will be eligible for parole in early 2021.

–  AAP