Michelle Boag says an "unhealthy obsession with politics" contributed to her decision to resign her membership from the National Party.
In a statement on Friday Boag revealed her resignation saying her 47-year-long passion for the party has put her on a "self-destructive path".
On Tuesday Boag confessed to leaking the details of a number of COVID-19 patients to former National MP Hamish Walker who resigned after admitting he gave the details to the press.
On Friday National's health spokesperson Michael Woodhouse disclosed Boag had also sent him "four unsolicited emails" containing more details.
"I recognised that the information in those emails was private so I did not share it with anyone else and I subsequently deleted them."
Boag says she recognises her decision to share the details was wrong and driven by her "distorted" view that the information would help National hold the Government to account.
"In fact it was harmful, not helpful and it is time that the National Party and I parted ways."
She says after joining the party aged 18 she has tried "way too hard" to support the Party but now realises she has become a hindrance.
"I have become an unhelpful distraction in the current political environment," the former Party leader said on Friday.
"I apologise to all those who have been collateral damage in my quest, both inside and outside the Party and I deeply regret my actions."
In an interview with Newshub on Thursday Boag said she believed the National Party could still win the election despite her scandal but "would not speculate" on whether she hurt their chances.
Health Minister Chris Hipkins appointed Michael Heron QC earlier this week to lead an investigation into the leaked information.
He said the scandal had a "ring of dirty politics to it".
Boag said she wrote to Michael Heron QC on Thursday night to advise him that towards the end of June she had sent several emails to Michael Woodhouse "comprising notification of a small number" of COVID-19 cases.
Woodhouse said he has made contact with Michael Heron QC to provide details to him in the event that it may be relevant to his investigation.
He also confirmed Boag is not the source of any previous information released to him in relation to the COVID-19 response - such as his unresolved claim of a homeless man spending time in a managed isolation facility.
Boag said she received the confidential information for both leaks as acting CEO of the Auckland Rescue Helicopter Trust (ARHT). But ARHT said Boag has never had access to any clinical or patient data.
Hipkins said the investigation should take a few weeks.
Boag also stepped down from Auckland Central MP Nikki Kaye's campaign committee.
You can read about Boag's history of privacy scandals here.