A registered nurse looked up the medical records of her former husband's new partner more than 40 times.
The woman has been found guilty of professional misconduct and suspended from practising for five months.
A decision by the Health Practitioners Disciplinary Tribunal said the registered nurse inappropriately accessed the electronic records of patients 85 times between May 2006 and March 2011.
That included accessing the records of her ex-husband's new partner 44 times in 38 days.
She was also accused of using confidential information obtained from the records on three occasions.
The nurses name and details of where she worked have been suppressed by the tribunal. She is referred to in documents as Mrs S.
The decision said in 2009 she had separated from her husband of 11 years, referred to as Mr S.
According to an agreed summary of facts, following their separation Mrs S became aware that her ex-husband had a new woman in his life, referred to as Ms B.
Ms B received a text message on her cellphone from an unknown number, saying: "You are with a married man who is desperately wanted back by his wife and three beautiful [children]. You are destroying their lives. How can you do it? He is not yours to take".
Mr S confirmed that text had come from his ex-wife's phone but said he had not provided her with his new partner's number.
The following year Mrs S "demanded to know why" Ms B's child now lived with his father, the decision said. Ms B said she was concerned how Mrs S knew that.
That prompted Mr S to email the district health board where his ex-wife worked, raising concerns she may have accessed medical records.
An audit of her computer use was carried out which revealed she had looked up her former husband's new partner 44 times over 38 days.
In total, she accessed the electronic records of 36 patients she was not providing care to, including Ms B's mother, and another woman her ex-husband had an affair with.
When questioned about her actions, Mrs S said she accessed the records on occasions when she needed to know where Mr S was.
She said she only wanted to protect her children, and it occurred when she was at a low point in her life.
Mrs S was dismissed from her role in April 2012.
Following a hearing in March, the tribunal found her guilty of professional misconduct. She was censured and suspended for five months.
She was also ordered to pay costs of $20,000.