Scott Guy's widow Kylee is considering leaving New Zealand if Ewen Macdonald is given a light sentence or released from jail on Friday.
The Herald revealed earlier today that Mrs Guy had penned a letter to Attorney General Chris Finlayson on Friday - a week before Macdonald is sentenced on six charges of criminal damage, arson and theft.
In the letter, also sent to the Prime Minister, Justice Minister and other politicians, Mrs Guy has asked that Macdonald be sentenced cumulatively rather than concurrently.
A cumulative sentence meant he would serve time for each offence one after the other. A concurrent sentence would see him serve his time simultaneously.
"Please from the bottom of my heart consider this letter. I have been living in this horrible nightmare for over two years and it can't keep going on," Mrs Guy wrote.
"Ewen Macdonald is a very dangerous, vindictive man and an extreme danger to our society and people.
He needs to pay for all of his individual and separate crimes and the hurt, pain and suffering he has caused; not only to myself, my husband and our children but to numerous other people within New Zealand.
"I am deeply afraid that the he will re-offend as he has delivered unthinkable vengeful and spiteful attacks. I am now alone and I must protect my children and for this I need a sentence that reflects appropriate justice.
"If the offender is granted a concurrent sentence it will not reflect the suffering he has caused to my family, neighbours and the community and will mean that he is able to escape the true gravity of his actions."
Mrs Guy wrote that she loved New Zealand and wanted it to remain home for her and Mr Guy's two children Hunter and Drover, who never met his father.
"But with what has happened and what I fear could happen, I will live my life in fear for the safety of Hunter, Drover and myself.
"Once Macdonald is released my only choice to provide safety for my family is to move from New Zealand, away from the support of family and friends; how is this fair?
"How much more pain do I and many others need to suffer as victims; as a country this is not right. New Zealand is regarded as a safe country that stands up for its people and we need to maintain this belief. Please look at this within your heart and help us," she wrote.
The letter was signed "Kylee, Hunter and Drover Guy".
Mr Guy was gunned down in his driveway in July 2010 and Macdonald was charged with murder.
He was acquitted this year after a High Court trial, but will be sentenced on six other charges on Friday.
But Macdonald, who was married to Mr Guy's sister Anna, admitted a further six charges - two relating to nasty attacks on Mrs Guy and her family.
On one occasion he and accomplice Callum Boe, a former worker on the Guy family farm, burnt a house on trailers ready to be removed from Mr and Mrs Guy's property.
Then, he vandalised and damaged their almost-complete new home, scrawling obscene graffiti on the walls and smashing every window.
A spokesman for Mr Finlayson's office said he had not yet seen the letter. Even if he had, it would be "improper" for the Attorney General to become involved in a court sentencing - which was up to the presiding judge.By Anna Leask @AnnaLeask Email Anna