Peter Conroy said the parents of all the children who survived and would be enjoying Christmas with them had to be thankful for what Chris Bielby, Dave Eland and Graham Nellist did.
He and his wife, Diane, echoed the views of the teachers and a senior detective that Wilkinson would have killed all the 25 pupils in the classroom if he had not been stopped.
They told a news conference at Cleveland police headquarters how the verdict came "as a bit of a shock" as they had been hoping Wilkinson would have been convicted of murder.
Mrs Conroy said: "I have come to accept it now. It wasn't what we wanted but we realise there was no choice on the basis of the evidence."
Mr Conroy spoke of viewing Wilkinson with a certain amount of "amazement" because he found it so hard to grasp how anyone could have carried out such an act. "But we personally feel he was in control of himself when he did it and we will always feel that."
Mrs Conroy said they were still just getting through life day by day, and added: "It will be like that for ever."
Asked what they would like to say to Wilkinson if they had the chance, Mrs Conroy replied "kneel down", referring to the frightening order the killer snapped out to the children in the class before he struck out with his knives. Mr Conroy replied: "I would just ask why? What have you achieved?"Reuse content