Members of a family of five in the other car, a Ford Territory, received moderate injuries.
The mother declined to be named but described the moments leading up to the crash on January 19.
She said her husband was driving home from a birthday party in Kaitaia about 10.30pm when the car driven by Nathan appeared in front of them.
"We were driving home and he was on the wrong side of the road and hit us head on. I got taken by helicopter to Whangarei Hospital. I have broken ribs."
The children are aged 3, 8 and 13.
"All my children have scrapes and scratches and my son has a broken collar bone. They are traumatised over the incident. It was horrific and horrible."
Barbara Hall, who lives near the crash scene, said she had learned later rescue workers had not breath-tested Nathan at the scene. Instead, she said efforts were focused on getting life-saving saline drips to the injured man.
She said a blood test taken at Whangarei Hospital after 1am came back under the limit.
Police were not available yesterday to confirm the timeline.
Hall said Mana Party members were waiting at the cordon wanting to retrieve a flag in the back of Nathan's car but were restrained by police.
Station officer Grant Baker said Nathan was not wearing a seat belt.
"There were paua shells scattered all over the road, a box of shells in the car and there were bottles of beer on the passenger seat and in the boot."
Witness Margo Wright, 17, who is a Students Against Drink Driving leader at Whangarei High, said she called the ambulance and, despite being in shock, took towels and water to the family.
She said the mother was clearly in pain. "They still had the [birthday] cake in the back seat. The 3-year-old boy was screaming."
Mana Party insiders said last night Nathan was a volunteer who had put up billboards, helped through the electorate and had painted the office after the byelection.
