Mrs Leigh, 43, a surgery practice manager, has now been warned by Aston school in Rotherham, South Yorkshire, that she faces prosecution and three months behind bars or a pound;2,500 fine for allowing him to skip lessons.
But she believes the school should be offering her and her son support rather than issuing prison threats.
"I am annoyed because in my opinion the school sticks to its truancy policy too rigidly without looking at each case to find out why individual children don't want to go to school," she said.
"Joel is not a wilful truant, but a boy suffering from severe depression as a result of what has happened to his dad.
"We have tried absolutely everything to persuade him to return to school, but it is hard to get him to leave the house at all. They can throw me in prison, but that is not going to help my son."
The school and Rotherham education authority insisted they had done "absolutely everything" to encourage Joel back to school, but that he had only attended two full days since September.
In a joint statement, they said: "He is allowed to come in at 10am and we have drawn up a special timetable for him which is only part-time. He has had a learning mentor to give him individual guidance and he is receiving educational psychology support.
"Every kind of support possible has been given and a lot of time and money has been invested."