Cudby had strangled the woman more than 40 times over the course of their relationship, the court heard.
She lost consciousness during one incident in June last year when Cudby wrapped his hands around her throat, then put her in a headlock and applied pressure for more than 10 seconds.
When she regained consciousness, she grabbed a knife and stabbed him.
Cudby then chased her with a spade, smashing a door in their Alexandra home, overpowering her before police arrived.
During another incident at their home, a friend heard a commotion and saw Cudby in a bedroom with his hands around the woman’s throat.
It took two people to pull him off her.
The assaults continued in Christchurch when Cudby threw her to the ground, spat in her face and picked up a nearby hammer.
When his father tried to intervene, Cudby grabbed a baseball bat and hit her in the ribs and legs.
Judge Elkin outlined how the abuse had started three months into the pair’s relationship and spanned 20 months. Cudby was in his early 20s at the time.
“It has had a very big impact on her; she is only 19, and, like you, very young. She is learning to rebuild her life,” the judge said.
The court heard Cudby had a drug habit which cost him around $200 a day and had also been found in possession of LSD, ecstasy and cannabis.
On charges of impeding breathing, assault with intent to injure, possessing LSD, ecstasy and cannabis for supply, possessing methamphetamine and unlawfully possessing ammunition, the judge took a starting point of six years and two months’ imprisonment.
Following credit for guilty pleas, lack of criminal history, his youth and rehabilitation efforts, he was sent to prison for three years and seven months.
Judge Elkin said Cudby would be subject to a first strike under the new Three Strikes law.
“If you commit a further serious offence, the consequences will be serious,” Judge Elkin told him.
She imposed a protection order in favour of the victim.
Al Williams is an Open Justice reporter for the New Zealand Herald, based in Christchurch. He has worked in daily and community titles in New Zealand and overseas for the last 16 years. Most recently he was editor of the Hauraki-Coromandel Post, based in Whangamatā. He was previously deputy editor of the Cook Islands News.