Martin Hughes sent dozens of sexually explicit and threatening text messages to his niece Michelle Doherty between 2011 and 2016 which led her to the brink of suicide.
Ms Doherty, now 44, even moved to Spain to escape the anonymous texts but was left devastated when the 68-year-old began to send text messages to her there.
The content of the messages was so disturbing that Judge John Aylmer told Letterkenny Circuit Court in Co Donegal that he only wanted a flavour of the messages.
Judge John Aylmer said this was one of the worst cases of harassment he has ever had to deal with saying the texts had a “devastating effect” on Ms Doherty’s life.
He also condemned Hughes for showing no signs of remorse and suggesting that he was justified in some way for carrying out the hate-filled campaign.
He added he did not agree with suggestions by the defence counsel that there were only 50 derogatory text messages sent to Ms Doherty.
Among the sexually explicit and threatening text messages sent to Ms Doherty was one in which he threatened to have her throat slit.
Hughes, a 68-year-old father and grandfather, of Quigley’s Point, Co Donegal, had pleaded guilty to a single count of harassment.
The court was told of an extensive investigation by gardaí to find the identity of the owner of the Northern Ireland unregistered phone used to send the texts.
Gardai finally tracked down Hughes who was hiding his phone in a cardboard box in his garage.
Speaking by videolink from Spain, Ms Doherty outlined the five years of her ordeal during which she said she became both depressed and suicidal.
She said on occasions she physically vomited when she read the texts and was paranoid as to who was sending them.
Passing sentence Judge Aylmer said he placed the charge in the mid-range of such offences and initially merited a sentence of four years.
He initially reduced that sentence to one of three years because of an early guilty plea.
He said that because of Hughes’s age and the fact that he came before the court with no previous convictions then he was reducing the sentence to one of 12 months.
As the judgment was passed Ms Doherty, on a videolink from Spain, wept.