Staff were "extremely" busy today as school broke for school holidays tomorrow, she said.
Earlier, the principal told the Herald that the email was received by the school last Thursday, from an external agency, wanting to ensure that a "vulnerable" student was being provided the necessary support.
"Unfortunately, as a result of human error, this email was accidentally forwarded to a cohort of students in our school. We sincerely apologise to the student involved."
The mistake was instantly recognised and steps immediately made to try to retrieve and delete the email.
"As principal, I put steps in place to mitigate the situation, which included suspending emails and deleting the specific email.
"This error resulted in us reviewing the processes within our school to prevent such a mistake happening again."
The school worked closely with outside agencies to ensure support was provided to students during times of stress or crisis.
Waikato police were investigating the alleged domestic violence.
Detective Inspector Karl Thornton, head of the Waikato Family Safety Network, said: "The manner in which this victim's details were shared with fellow students is extremely unfortunate.
"While steps are under way to ensure such a mistake can't happen again, the priority for all the organisations now is to ensure the student receives any support and services necessary," Mr Thornton said.
He accepted it was a result of human error.
The family safety network, which was recently set up, is a collaboration of government and non-government agencies which helps to respond to incidents of family violence.
Mr Thornton said that as a new, innovative initiative, the network was happy to work with schools or any other organisations "who may like advice on how to improve processes regarding student safety and welfare".
Katrina Casey, Ministry of Education's head of sector enablement and support, said their staff met with police and the school principal as soon as they were alerted to the breach of privacy.
"At the meeting we determined the principal had taken all reasonable steps to protect and support the individual student, as well as reviewing its privacy processes to ensure such an error cannot happen in the future.
"It is extremely unfortunate that human error resulted in a privacy breach and the school has treated the matter very seriously. We remain in close contact with the school offering support as required."
Ms Casey said protecting the privacy of students was as much a priority for the Ministry as it was the schools.
