A bus driver whose actions killed 10 people and injured 25 others on their way home from a wedding has told a sentencing hearing he "can't forgive" himself for what happened but that he "wasn't negligent".

Indigenous readers are advised that this article contains the names and images of people who have died.

Ten people died and 25 others were injured when the bus flipped on its side and hit a guard rail at Greta in the New South Wales Hunter Valley on June 11, 2023.

The driver, Brett Andrew Button, pleaded guilty in May to 35 charges relating to dangerous driving occasioning death, dangerous driving occasioning grievous bodily harm, driving furiously, and causing bodily harm to survivors.

Button is speaking publicly for the first time today as part of his sentencing hearings and told the court he had been taking the opioid tramadol since 1994.

"I've tried to figure out the words to say I'm sorry, but how do you say you're sorry for such a horrible tragic event that has ruined the lives of hundreds of people," he told the court.

"I can't believe I caused this, I never meant to cause it and every single person that died and was injured and everyone involved in this, I truly wish it never happened and I could apologise where people actually believe me.

"I live with this every day and I hate myself.

"I've caused parents to have to bury their children, which has been my biggest nightmare all my life, and now I've done it to so many families.

"I'm sorry to everyone involved, including the police and everyone, my family — I've shamed everyone."

'I take responsibility'

Wearing a dark suit and tie, black rimmed glassed and with cropped hair, Button gave evidence over the course of about an hour.

The 59-year-old said he had been made aware by a pain specialist that he was at risk of addiction a year before the crash.

When asked by his barrister Paul Rosser KC if he felt he was addicted, Button said he was "certainly dependent".

When further questioned, Mr Button said he had no perception on that night the drug had impaired his driving.

Button told police on the night he was "going slow enough", but today said he accepted he was going too fast when the bus tipped and rolled at the Greta roundabout.

"I take responsibility for the death and injuries, it was no way purposeful and I wasn't negligent," he told the court.

Button said he had become a pariah in the community.

"People in supermarkets and so forth, in line-ups, talking about me, pointing the finger and saying horrible things," he told the court.

In his evidence, Button said the roundabout where the bus rolled was poorly designed.

During a cross-examination, Crown prosecutor Katharine Jeffreys asked Button if he was trying to blame the roundabout for the crash.

"Are you trying to suggest the design of the roundabout played a role?" she asked.

"I don't think it is the perfect roundabout, that is for sure," Button replied.

"Do you agree you have been trying to find explanation other than your own conduct?" Ms Jeffreys asked.

"I blame me," Button said.

Pain killer use questioned

Judge Roy Ellis intervened in the proceedings to ask questions about Button's tramadol use prior to the accident.

"Why did you think the doctor was limiting the amount of tramadol you were to take while driving a bus?" Judge Ellis asked.

"Because they thought I was addicted," Button replied.

"Well, if you are addicted to chocolates it doesn't stop you driving a car properly," Judge Ellis said.

"Why then do you think doctors said, 'Don't use this'?

"Why do you think they limited that?"

"In hindsight, they thought I was a risk," Button replied.

Button also admitted to "joking about rollercoasters" before saying "this next part is going to be fun" as he accelerated through the roundabout, tipping the bus.

Victims and families stared at Button as he returned to dock, flanked by court sheriffs.

His family watched the proceedings from elsewhere.

When discussing Button's likely punishment, Judge Ellis was frank.

"It is a unlikely any sentence I impose is going to keep everyone happy," he said.

Remorse recognised

In her closing submission, Crown prosecutor Katharine Jeffreys made note of Button's remorse.

"The offender has expressed his sorrow and remorse for the consequences of his actions … and it is accepted he clearly understands the effect of his conduct," she said.

"But, Your Honour, the Crown says you would have caution in finding he has in fact fully accepted responsibility."

Judge Ellis said he thought Button had "expressed genuine remorse and contrition".

"He has signed agreed facts and that does show that he is the person responsible," Judge Ellis said.

Button turns 60 next month and Judge Ellis said prison would not be easy for him.

Impact statements considered

Judge Ellis will consider 40 victim impact statements as part of his sentencing, which he is expected to deliver on Thursday.

Singleton locals Nadene McBride, her 22-year-old daughter Kyah, Andrew Scott, 35, and his wife, Lynan, 33, Tori Cowburn, 29, and Rebecca Mullen, 26, all died in the crash.

Also killed were Kane Symons, 21, from Tasmania, Zach Bray, 29, from Byron Bay, Angus Craig, 28, from Queensland, and Darcy Bulman, 30, from Melbourne.

Among the family members and survivors that addressed the court over two days, was survivor Jason Junkeer, who recalled an "overwhelming sensation I was going to die" as he worried about how fast Button was driving.

On Monday, Graeme McBride told the court of his grief at losing his wife Nadene and daughter Kyah in the crash.

"My family was my proudest achievement, and my girls the most important thing in my life … which have now been taken from me," he said.