Cooper has put his $2.2 million Karaka mansion on the market and has already moved away from his parents to Waihi with his new wife, Sharie Marshall.
The 35-year-old bought the sprawling mansion a month after his win, as well as a million-dollar property just around the corner for his parents, Kevin and Shirley Cooper.
In the most telling evidence of the family split, public records show properties bought just after the win - which were in the names of Trevor, his father Kevin and sister Sharon - have since been transferred into the names of just Trevor and wife Sharie.
Trevor Cooper appeared on national television shortly after his win with his parents and said his windfall would be used to benefit the whole family.
"My family has always been there for me," Trevor said in an early interview.
"My mum, my dad, my sister, my brother-in-law, my niece, my nephew. Now it's time to repay them for the times they have been there for me."
But within a year the close relationships seem to have broken down, though both the parents and his sister continue to live in the properties.
Estranged family members refused to comment and Trevor himself could not be contacted. But a source close to the Lotto winner said the family were distraught about the way things had turned out.
It is understood other friendships have also suffered.
Posts made on the Facebook page of the Te Kauwhata flatmate Trevor was living with when he won Powerball, Lisa Sampey, suggest she too is bitter.
A photo of Trevor and wife Sharie on their wedding day features, along with some vitriolic comments. In another section of her page, she writes about her experiences post the Lotto win: "It's nice to be s*** on by a so-called friend."
At the time of the win, Trevor said although he wasn't in a relationship with his flatmate, he thought of her daughter as his own.
Since his win, Trevor has indulged his love of motorsport with a series of purchases, including American streetcars, sprint cars, offroad cars, a speedboat and numerous trips to the United States to race in prestigious events.
He has also bought at least five properties, including houses in Beachhaven, Pukekohe, the Karaka mansions and a 113ha dairy farm in Sharie's hometown of Waihi. It has been a multi-million dollar spending spree.
Sharie, who was engaged to Waihi local Michael Capper in July last year, married Trevor at the Karaka property in February, just two months after they announced their December engagement. His links with his family were strained then, and some members did not attend.
The four-bedroom and four-bathroom Karaka house went on the market on Friday and is listed with Harcourts.
Trevor spared no expense turning the purpose-built equestrian property into a motorsport lover's dream.
The real estate advert states the owners have "Gone South".
"Originally purpose-built for equine, this property has also housed a large array of motorsport vehicles in recent times, giving a new meaning to horse power," the blurb says.
Tenders close on the property, with a council valuation of $2,050,000, on September 12.
Recent extensions to the property include an upper level master suite, integrated security system, a solar-heated in-ground swimming pool with retractable cover, summer house and sauna.
It is understood Trevor spent more than $800,000 upgrading the property, which also has six-car internal access garaging, and two barns.
Late last year Trevor and Sharie bought the dairy farm in Waihi. The secluded farm, set in native bush, included a three-bedroom house, stream, swimming hole and milking sheds and cattle.
Despite their wealth, the couple took out a loan this year through their company TR & SA Cooper to buy livestock from NZ Farmers Livestock.
Father Kevin is still listed as a director in that company in spite of the family issues.
The Herald on Sunday wanted to discuss the family troubles with Cooper, but earlier this year was asked by his legal firm, Rennie Cox, to make no contact with their client.
Partner Graeme Cox was emailed on Friday that the paper was working on a significant story, and told it would only be fair to Cooper to be able to put questions to him.
Cox did not respond to the request by late last night.
Winners advised to seek help from professionals
Winning a large amount of money is life-changing and comes with stress and expectation, says registered psychologist Sara Chatwin.
And it often changes family dynamics, she says.
"There can be certain expectations family members may have of the member who has come into the money," Chatwin says. "Nothing stays the same."
She stresses she knows nothing of Trevor Cooper's situation, but says she has counselled people who have become overwhelmed after winning big.
She advises them to stick to a routine and avoid making too many life changes at once.
"Get in touch with professionals who can give good advice and don't fall into the habit of playing games with people."
Who to tell - and when - should also be carefully considered and expert advice sought.
"When people go public, anyone who receives a large amount of money has to be sure it is the right decision because they will come under scrutiny, there is social judgment and some people who want to get to know them have a motive," Chatwin says.
NZ Lotteries provides all big winners with the book This is not a Dream which offers emotional and financial advice.
