Pashley had supported her decision to return home from Australia six years ago and accompanied her and the boys as they made a fresh start.
However, since then his abuse had escalated.
She said she had always worked hard to provide for her boys and owned her own home, but Pashley had wiped that away in one night.
''I couldn't believe Billy would hurt us in that way, to send everything we owned up in smoke.''
Addressing her former partner directly, she said: ''You are a gutless and spiteful person. As you know, our whānau has already lost so much.''
While Pashley had a roof over his head and three meals provided a day — he has been in custody since his arrest — she had been forced to rely on the charity of others for the first time in her life.
She also had to pay rent while still paying rates for a property she and her sons could not live on.
Many of the items lost, such as photos, paintings and gifts, could not be replaced.
''But you didn't just take the material side of things, you took our lives,'' she said.
Neither the house nor contents were insured.
Judge Gene Tomlinson said he was ''pretty disgusted'' with Pashley's behaviour and the harm he had caused to people he once cared about.
While arson carried a maximum penalty of 14 years' jail, Judge Tomlinson said he was surprised by the sentences in case law for destroying a family home.
That meant the length of sentence he could impose was constrained.
Starting with a sentence of four years, he reduced it for Pashley's guilty plea — which came after a sentence indication on May 12 — as well as his remorse and steps to address his alcohol use, arriving at a jail term of two and a half years.
The Crown also sought $40,000 in reparation to be paid to the victim, though it would be ''nowhere near enough'' to replace what she had lost.
Judge Tomlinson said Pashley would be unable to pay while he was in prison and once he had been deported New Zealand authorities could not force him to stump up.
However, it was still important to make the order, he said.
''If he is genuine in his remorse, and making good the harm he has caused, he will at least make a start at paying the reparation I have ordered ... then he will go some way to owning this offending and taking responsibility for it.''