The president of the ATL section of the NEU teaching union has spoken about how workload "burnout" left her crying on the way to work and caused her to walk out of the classroom.
Niamh Sweeney said the education system was in the midst of "the biggest recruitment and retention crisis" it had ever faced.
Addressing ATL's last annual conference, Ms Sweeney said: "Four years ago, I walked out of the classroom, left students mid-way through their sixth form and felt horrifically guilty. I still do. I feared at the time that I was leaving forever. I was due to leave at the end of term for a job with the local authority, but two weeks before the Easter break my doctor signed me off with burnout. I was spent. I had a chest infection, had lost my voice and just couldn't put myself through it anymore.
"At the time I felt driven out by a toxic working and learning environment, an environment stripped bare of funding and resources, an environment where staff were exhausted. Colleagues shared stories about crying on Sunday evenings before returning to work – I cried on the way to work.
Exam system 'sucks the love out of learning'
"I felt driven out by workload pressure and a micro-management regime. School leadership grew less confident in themselves and in an accountability system that could, in one visit, end their career and lose the establishment its reputation.
"Add to that a testing and exam system that sucks the love of learning out of everyone. A system that excludes, off-rolls and ignores those with most need and those must vulnerable to discrimination and exploitation. I left."
Ms Sweeney said she had returned to teaching through the support of the ATL. "Without the support, advice and guidance from my branch secretary, regional official and the staff at the end of the phone, I wouldn't have been able to stick my head above the parapet," she explained.
"I wouldn't have had the confidence to call for a workload survey, or approach my line manager about the chronic lack of resources and support being given to my subject."