"I know he has no boundaries as to what he will do to me."

Those were the words of a Hawke's Bay woman who unwittingly got engaged to a violent stalker and learned about his "dark side" and criminal history after she tried to break off their two-year relationship.

Hayden Esmond Reginald Howard Keil's response was to attack her, punching her eight times in the head before grabbing and holding her down by the neck on a bed for about 10 seconds.

In the following days, Keil, 29, put a tracker on her car.

She spotted his vehicle in her rear-vision mirror. When she got out of her car to seek help at the Hastings police station, Keil drove onto the footpath and directly at her before hitting a sign.

Minutes later, he was the subject of a brief police pursuit which had to be abandoned.

The following day, Keil broke into the woman's house and moved some of her intimate possessions. Alerted by the woman and a concerned neighbour, police went to the property and found him on the roof.

Even after being charged and sent to Christchurch on electronically-monitored bail, Keil continued to send social media messages to the woman in breach of a protection order.

He pleaded guilty to 10 charges including assault with intent to injure, assault on a person in a family relationship, assault with a blunt instrument, wilful damage, reckless driving, burglary and breaching a protection order.

Judge Gordon Matenga read part of the woman's victim impact statement in the Napier District Court this week, saying she feared for her life when Keil attacked her in March this year.

"Up until that time (of the attack) you had not given her any idea or inclination that you had this dark side to you," the judge told Keil in sentencing him to seven months of home detention.

The woman was also unaware that Keil, who is the listed director of a business running an R18 adult entertainment directory online, had a history of stalking and violence.

Only later did she do an internet search of his name and discover a copy of an Ashburton Guardian court report from 2016, in which a judge called Keil a stalker for his "erratic behaviour" towards a former girlfriend and told him he needed help with his "bad attitude towards women".

He was in that year sentenced to intensive supervision for assaulting a female, wilful trespass and four breaches of a protection order.

The Napier court this week was told that Keil had spent time in prison in Australia in the years since 2016.

Exactly what he did in Australia was not detailed in court, but Judge Matenga said his offending in both countries "shows that you have a tendency towards this type of behaviour".

The judge said this tendency needed to be dealt with "or it will get worse".

Police argued for a prison sentence for Keil, but defence counsel Stephen Yee said home detention would allow him to continue on a path of rehabilitation that he had already started voluntarily with counselling.

"Prison is not going to help anyone in this regard," Yee said.

"It wouldn't do any good for the rehabilitation of Mr Keil, which he accepts he needs."

He said the social media messages Keil sent to his victim were apologetic, not abusive, and he was not trying to get her to drop the charges.

Judge Matenga, however, said there were seven messages, and while they were not overtly threatening they were "unwanted and certainly illegal".

Judge Matenga said he accepted that Keil's remorse was genuine.

"I do think that you are appalled by your own behaviour, but clearly there are some things that you need to do to make adjustments, so that this does not happen again," he said.

Judge Matenga read parts of the victim impact statement in which the woman said she was missing and grieving for a fiance "who is not the person I thought he was".

She was still scared, still had flashbacks, constantly checked her rear vision mirror while driving and was vigilant to every noise at night.

"It is important that you know the impact," the judge told Keil.

A pre-sentence report recommended a home detention sentence and Judge Matenga said it would be served at a Christchurch address.

After seven months of home detention, Keil will be subject to six months of post-detention conditions, will have to do a Department of Corrections rehabilitation course and undergo an assessment for a stopping violence programme.

He is not allowed to consume alcohol or non-prescription drugs, and he is not allowed to contact his victim.

Judge Matenga gave sentence discounts for Keil's guilty plea and matters raised in a cultural report, which showed he had limited education and was subjected to violence in his early life, including violence from the police.

The court was told that Keil spent 68 days in prison on remand, and 67 days on electronically-monitored bail with a 24-hour curfew.

Judge Matenga ordered reparation of $1149 for a wing mirror on the woman's car, which Keil broke after the bedroom assault, and $503 for damage caused in the burglary.

According to the Companies Office, Keil is the sole director of a company called Adult Play World, an adult entertainment directory which has an R18 website.

It is also understood that he intended to set up a party bus business in Hawke's Bay. Last month, while on bail, he registered a new company called Bay Party Bus Ltd.

- Ric Stevens, Open Justice