The principal of a special school walked in on a female care worker who had been having sex with a 17-year-old boy, it has emerged.
Amanda McNally, 41, was found hiding behind a bed with the half naked teenager in his room at the boarding school in Hertfordshire.
When the principal walked in, he saw a silhouette behind the bed. The boy - who has a mental age of 13 - suddenly emerged without his top on.
McNally then appeared saying they had been looking for a paint brush as they were decorating his flat, St Albans crown court heard today.
Prosecutor Michael Speak said the boy, who suffers from epilepsy and is subject to seizures and depression, confessed to having sex with McNally the next day.
The police were called and in a recorded interview the boy said: 'She was being nice but she took advantage of me.'
He said they had penetrative sex in the flat. He said sex had happened before between them, but she had only been charged with one offence. DNA tests confirmed that they had engaged in sexual activity.
Mr Speak said McNally, who has a 17-year-old son of her own, had worked as a house care assistant at the school for 3 years, with a 6 month break.
'Her responsibilities were to get the children up, prepare their breakfast, to get them to have a wash and clean their houses and do the shopping.
'At half past three they would return from school and her duties would be to make tea. The care workers are described by the Principal as surrogate parents,' he said.
In a victim impact statement the boy said he had been left feeling 'insecure and felt suicidal waking up at night.' He went on: 'She said she was my friend. I can’t trust her. Now I am in a black hole.'
McNally, 41, from Ware, Hertfordshire, admitted sexual activity with a child while in a position of trust on February 22 this year. She gave no comment to police interviews. She was of previous good character.
Stephen Requena, defending, asked for credit for her guilty plea. In a text sent to the boy earlier she had said the relationship should end.
At the time her friendship with the boy was the only happiness in her life, he said. She had married at 23, but separated from her husband in 2005. In January this year they divorced after he said he wanted to marry another woman.
He said McNally was supported by family and friends and handed the judge references which described her as 'caring and loving.'
Judge Stephen Warner told her: 'You were in a position of trust. You befriended him and his family. It was not an isolated incident and only stopped when you were discovered.
'This was a highly inappropriate relationship. He was 17, you were 41. He was vulnerable and compliant. You took advantage to enter into this relationship. You knew it was wrong but you persisted.'
He jailed her for 14 months and banned her from ever working with children. McNally must sign the Sex Offender Register for 5 years.