The estranged wife of convicted murderer Hayden McKenzie has been sentenced to community work after she admitted spitting into a police officer's mouth and kicking two officers in the groin.

Kylie Jade McKenzie, 28, of Westport, admitted in Westport District Court obstructing police, resisting police, and three charges of assaulting police.

Prosecuting, Sergeant Mark Harris said McKenzie, a solo mother, had been at the Cosmopolitan Hotel on New Year's Eve drinking with her family.

Her family had left the bar and taken their glasses of alcohol onto the street.

After a scuffle, police had arrested McKenzie's brother and she became aggressive.

She tried to pull police from her brother to stop them handcuffing him. She then spat directly into a police officer's mouth and continued to shout abuse. After attempting to run from police, she kicked two officers in the groin.

Defending, Doug Taffs said his client had been under an enormous amount of stress.

She had "lost the plot (and) everything snapped" when she saw police arrest her brother.

Her husband was in prison for his involvement in two murders: Korean backpacker Jae Hyeon Kim in 2003 and Westport man James Bambrough in 1999.

During the period when both murders occurred, he was a member of a violent neo-Nazi gang.

His client had been desperately in love with Hayden McKenzie and felt badly let down, although she had since filed for divorce.

Mr Taffs said McKenzie had helped police with their inquiries into her husband's involvement in the murders and had faced threats as a result.

Judge Emma Smith acknowledged the stresses McKenzie had faced in her life.

However, that did not justify her behaviour.

"I cannot abide spitting, it's designed to cause distress and it did," Ms Smith said.

McKenzie pleaded guilty to all charges and Judge Smith convicted her on three charges of assault and sentenced her to 80 hours of community work. She was convicted and discharged for obstructing and resisting police.