Since the crash, the father-of-three has been sheltered on a rural Canterbury property by friend and fellow Dutchman Arjen Buter.
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Last night, Buter said Appelman, known as Jan, has not spoken publicly because he can't express how he feels but is "absolutely sorry for what he has done".
"We've got kids the same age. It will hurt for the rest of his life."
Appelman is a general manager of an international firm that sells agricultural dry storage facilities and travels often to New Zealand.
On May 30 he arrived in Christchurch and rented a car, but just a few kilometres from the airport crashed it while fiddling with his GPS. The next day, he hired a Subaru from another firm and about 3.55pm drove through a stop sign at a rural intersection near Rakaia at about 100km/h.
Appelman, who says he did not see the sign, ploughed into the Summerfields' Volvo on the passenger side, killing Mrs Summerfield and the youngsters on impact.
Mrs Summerfield's husband, Shane, suffered broken ribs, a ruptured diaphragm, lacerated spleen and kidney, left side hemothorax and torn aorta.
Abi Hone and Ella and Sally Summerfield.
The 48-year-old dentist, supported by his son Sam, read an emotional victim impact statement at Appelman's sentencing in Christchurch District Court yesterday.
He spoke of the "unbearable" pain and said he hoped Appelman's guilt would "remain with him forever".
"Written words will never express the devastation [Appelman] has caused so many people," he said.
"For us to remain here in Christchurch, we will never have a reprieve from the loss of the three girls. It will live on like a recurring nightmare."
Judge Saunders sentenced Appelman on three counts of careless use of a vehicle causing death, one charge of careless use of a vehicle causing injury, and one of careless use of a motor vehicle.
He banned him from driving for 15 months and ordered him to pay Mr Summerfield $25,000 of emotional harm reparation.
The court heard that Appelman had already paid an undisclosed sum to the Hone family.
The Summerfields had met Appelman in a restorative justice conference and came away feeling he was not remorseful.
His lawyer, Phil Shamy, assured the court he was. "There is nothing that Mr Appelman can say, nothing he can do, there is nothing he can offer that will ever make up for the harm he has done," Mr Shamy said.
Mr Buter said Mr Shamy had advised Appelman not to speak to the media, but the lawyer had "expressed Jan's feelings well".
"It wasn't lip service," Mr Buter said. "He's not a man that easily talks about his emotions, or is able to express in words what he feels."
Appelman's wife, Sylvia, said her husband -- who has undergone counselling -- didn't want to speak about what happened. "He doesn't see the need," she told APNZ last night.
If Appelman returns to New Zealand he will have to obtain a New Zealand driving licence and satisfy authorities that he's safe. A charge of careless driving causing death carries a maximum penalty of three months' jail.
Dr Chris Gallavin, dean of law at University of Canterbury, said it was rare for prison terms to be handed down in careless driving cases.
"More often these cases are treated as a tragedy for everyone involved."