"I'm waiting for someone to come over and say `this is a big joke' because I don't want to believe."
Ms Schmidt also has two younger sons and a daughter.
"Everyone was called to meet," he said. "I saw everyone crying and I didn't know what was wrong. My dad came over and said, 'it's your mum'."
He added: "It hit me and a part of me was taken away and I can't get it back."
His mother had given the world to her family. "She was always kind and she was always happy. She would make sure she did anything she could to make people happy. She was beautiful - she didn't deserve this."
Ms Schmidt was holidaying in New Zealand with her Australian partner. It was her first trip out of her native country. "She always wanted to go to New Zealand," Mr Caughey said.
"I've always wanted to go as well. [Her death has] given me more reason to go so I can be there, where she was."
Ms Schmidt had only been in New Zealand for a few days when the tragedy occurred.
Police are still trying to piece together what happened to Ms Schmidt in the hours before her death. Mr Caughey said few details had been shared with the family.
He had not heard from his mother's partner, but said the pair were "really, really close" and he believed they were recently engaged.
The family had not yet decided on a date for Ms Schmidt's funeral, but it would be held in Queensland, he said.
However, the family's first priority was to bring her body home. "I want to hope she is in a happier place," Mr Caughey said.
Detective Sergeant Mark McCloy said a driver had alerted police after hitting Ms Schmidt.
Police have spoken to the driver - who is now being assisted by victim support - and several other people in relation to the incident.
Four vehicles are under forensic examination and a number of locations of interest are being looked at.
Investigations also include Ms Schmidt's movements in the hours and days before her death.
