"He's now having bad dreams about you chasing his mum ... you did this to him and I'm having to pick up the pieces.
"You left a little boy without his mother, he was the only person she truly loved.
"I wish I could make you feel our pain. I hope you know what you have done and how you have affected our lives."
At the High Court today Justice Graham Lang said he had no other option but to impose a sentence of life imprisonment, taking into account Hepana's previous convictions and lack of remorse.
The public gallery was filled with about 30 friends and family of Ms Cooper, who had travelled to Auckland from Te Hana and Rotorua to witness the sentencing of her murderer.
Ms Cooper had entered a relationship with Hepana last July, until it came to a violent end in November, Justice Lang said.
He said Hepana attacked a vulnerable woman living alone in her house in the middle of the night while a trespass order was place against him.
Crown lawyer Natalie Walker told the court Hepana had five previous convictions for assaulting women and two for wounding with intent to cause grievous bodily harm.
The grievous bodily harm convictions stemmed from an incident where Hepana attacked his half-brother with a tomahawk and stabbed another man in the abdomen with a knife. He was jailed for 10 years over the incident.
Ms Cooper texted her sister before she was killed, saying someone was "creeping around" her house in Te Hana, just north of Wellsford.
Ms Walker told the court that shortly after midnight, Hepana went into Ms Cooper's home and strangled her before dragging her outside her house.
When she came to, he strangled her again, rendering her unconscious, before beating her around the face and throat with a rock, killing her.
Hepana's lawyer Michael Levett said he had been instructed by his client not to argue for any form of sentence reduction.
