The other driver and his youngest son emerged with cuts and scratches. Stuart's vehicle was destroyed.
"When I woke up my heart was pumping and I couldn't get a hold of Stuart on the phone," Lulu told the Herald on Sunday. "I was overcome with a very weird feeling and I just knew something wasn't right. I texted and called him but got no reply, which was unusual."
After she returned from a soccer match in which her 12-year-old son Lloyd played, police delivered the news that her husband of 23 years was dead. "He was such a quiet and loving family man and it is hard to accept he was taken like this," Lulu, originally from the Philippines, said. "The kids are devastated."
Northern Rural Haulage boss Doug Wilson, who owns the truck involved, said the Whangarei father and son who survived are still in a state of shock. Wilson said his employee was delivering road metal to Waipu when the accident happened.
The driver had told him the light truck crossed the centre line and drove into the path of the 11-tonne vehicle on State Highway 1, about 30km south of Whangarei.
"My driver sometimes has his son, who is only 12 or 13, with him on a Saturday and it was a miracle both weren't killed or badly injured," he said. "If he hadn't been in such a big truck, things would have been a lot worse." Wilson had arrived at the scene about 8am after his shaken worker phoned for help.
By then emergency services had closed the road. Williams was declared dead at the scene.
Inspector Murray Hodson, Northland road policing manager, indicated it was too early to say what had caused the accident.
A police serious crash unit investigation was under way.
Lulu held a funeral for her husband in Papatoetoe on Thursday, attended by more than 100 people.
"Stuart had worked as a driver for many years and was meticulous about checking his truck," she said. "I don't know if he fell asleep behind the wheel or something, but in the blink of an eye three kids have lost their dad and I have lost the man I loved so much. We don't blame anyone else. It is just tragic."