She was banned from working with children for life and ordered to sign on the sex offenders' register for ten years.
Millman's husband, who owns a coach company, attended court and was said to be "standing by his wife", according to her barrister.
Prosecuting barrister James Byatt said Millman's initial contact with the youth was on Facebook and was of a friendly nature prior to the two offences between September and November 2010 and January and March 2011.
He said: "She took a caring attitude and he confided in her. He felt he could unburden himself and they had hugs. After rows with his mother he felt he could go to confide in her."
Millman met the boy on one occasion.
Mr Byatt added: "The nature of the communication changed and it became more sexual. She would comment on his good looks.
"There was a message for him on Facebook every day and texts of a sexual nature were sent. There were so many he asked her to stop it when he was at school."
Mr Byatt gave details of the first sexual encounter when she picked him up in her Jeep. On another occasion he climbed out of his bedroom window and again she picked him up in the Jeep in which they had intercourse.
Detectives later discovered evidence on a webcam of her revealing herself and making provocative statements to one of the boys.
She was arrested on May 24 and told police the contact had not been sexual - just kisses.
She told police: "He is chatty and bubbly, just like me."
Mr Byatt said the youth could not consent to having sex and she should have been aware of his emotional development.
Having had contact with his mother in the past, she ought to have realised the boy's vulnerable state, he said.
In a statement on the impact on her son, his mother said there had been upset and he was "more insecure".
The statement said the youth felt embarrassed and partly to blame.
The defendant, dressed in a blouse and black trousers, sobbed throughout, with her head bowed.
For Millman, Simon Hirst said his client was adamant it was no fault of the teenager.
He said: "She feels she has let a large number of people down. Her life will never be the same.
"There was no element of planning. She behaved totally inappropriately and she takes total blame."
Mr Hirst said his client felt low self esteem at the time. Mr Millman went to work at 6.30am, until very late and she gained attention from the youth.
Mr Hirst said: "The relationship may have compensated for shortcomings in her marriage. She is remorseful and accepts full responsibility."
Judge David Tremberg told Millman: "You were in a position of trust. You could not have failed to know that any form of amorous relationship, let alone full sexual relations with a boy 30 years your junior would have been wholly inappropriate and illegal.
"You were prepared to engage him on Facebook, by telephone and texts.
"At the time you were involved he should have been concentrating at school. He did not need to be distracted."
He added she had "willingly" exposed herself to the boys on the internet and that the incident had harmed the boys relationship with his mother.
Following the hearing, investigating officer Detective Sergeant Stewart Watson said: "Female sex offenders should not be treated any differently. I am satisfied the court has recognised that."
He said officers at Humberside Police safeguarding team were keen to hear from any other victims: "I would urge victims of sex offences not to be put off by the justice system. There are support mechanisms in place."