"My drinking on that night was out of control," she wrote.
"I feel very sad and bad."
Her scars from the May 1 incident had since healed and she said she took the blame for Te Amo's violent outburst - "because I smashed up his car".
The Dunedin couple had been working that day and the defendant had become grumpy as he had to help his partner with some deliveries.
When they returned home they drank until late.
They argued about damage to Te Amo's vehicle, money and other minor matters until the defendant lost his temper.
He said he would not go back to jail unless he murdered her.
The attack began with Te Amo approaching the victim from behind and forcing his arm across her throat, restricting her breathing.
"The defendant was yelling at the victim and calling her fat and calling her names," court documents said.
Te Amo then bit the woman on the arm and followed her around the house, preventing her from using her phone to call police.
After more alcohol was consumed his rage erupted again.
Te Amo punched his girlfriend at least once in the face, causing a deep laceration to her lip, which bled profusely.
When police arrived they found blood all through the house.
He told officers the woman was "prone to accidents" and could not explain why he, too, was covered in her blood.
Counsel John Westgate said Te Amo had denied the assault at first but now wanted to "man up".
In a letter his client wrote to the victim, he squarely took the blame for what happened.
"You don't need to own this, I do," he wrote.
Judge Crosbie said there were positive reports from the prison that Te Amo had been compassionate and supportive with other prisoners.
But the defendant could not hide from his 16 pages of convictions, 18 of which were for violence, the judge said.
Last year's attack came while Te Amo was serving release conditions designed to stop him reoffending, the court heard.
The judge imposed a prison term of two years seven months.
"Because of the need to protect the public", a minimum non-parole period of 50 per cent was added.