"It's been awful, but I was lucky to meet these lovely people."
On January 29, Greenwood was riding a motorcycle with partner, Auckland socialite Nicola (Nikki) Gapes riding pillion on the Kaipara Coast Highway northwest of Auckland.
They were on their way back home from a romantic weekend in Russell when they crashed. Another motorbike and a car were involved.
Police confirmed that the businessman has been charged with careless driving causing death.
Speaking to the Herald on Sunday, Greenwood described the death of his partner as "an absolute tragedy", adding he was "not a reckless person".
The couple loved riding their motorbike on the open roads and Greenwood said the tragedy happened after they had been riding on a "clear, straight road". He said "conditions were good" and that speed wasn't involved.
Greenwood was badly injured. He was knocked unconscious and suffered broken ribs and internal injuries. He was hospitalised for three days.
His wife, Toni Nelson, died of cancer aged 50 in March 2015.
Greenwood thanked friends and family for the ongoing support, especially his three children Holly, Liberty and Nelson.
"There have been lots of tears, but they've been incredibly brave," he said.
"This time has been incredibly traumatic for my three kids — they've just lost their mum. And they loved Nikki, too."
He said he regularly stays in touch with Gapes' children.
"All our kids are great friends — we message each other all the time. They are lovely. I am really concerned for Nikki's parents, too. I worry about them all the time."
For now, Greenwood is taking things "day by day, hour by hour" and is prepared to fight his charge.
"I don't think I ever will get over this. Nikki is beautiful inside and out in every way. I miss everything about her ... everything. I loved her."
Gapes and Greenwood met in their twenties. Gapes and her former husband, property developer Tony Gapes, were close friends with Greenwood and his wife.
Greenwood and Tony Gapes were pallbearers at Nikki Gapes' funeral in Parnell.
After her death, Tony Gapes told the Herald on Sunday that she was a "wonderful mother" to their kids Estella, 15, Mia, 13, and 10 year-old son Sam.
"She was completely devoted to them", he said at the time.
"Nikki was a fun, loving, kind and caring person who was an amazing mother to our three beautiful kids. They were the light of her life and she was incredibly proud of them. We are all going to miss her."
The pair were married for 10 years before they separated about eight years ago.
Gapes was a full-time mother and fashion blogger for Personal Style Guide. Two years ago she designed a capsule collection with Kiwi designer Yvonne Bennetti, whom she met as a client in the boutique.
"Nikki was fun, vivacious and always happy. She was inspiring and a beautiful person to be around," said Bennetti.
Greenwood's Kawasaki ZX motorbike was written off in the crash, adding: "I don't own a motorbike anymore. I sold them all. I haven't been on any rides and am not interested getting on a motorbike — it brings back too many sad memories".