The man has permanent name suppression, as does his victim, a now-36-year-old man.
Judge Bruce Davidson said the "extremely vulnerable" victim met the defendant on an internet dating site in 2013, and the pair began a sexual relationship which initially involved the defendant paying the victim.
This later changed to the defendant giving the victim gifts and other financial support.
In 2018, the victim ended the relationship.
"Over the next two months, from February to April 2018, you launched a campaign of blackmail and of posting harmful digital communications against and about the complainant."
The campaign included emails, letters, social media posts, phone calls, voicemails and civil court proceedings.
The defendant continually threatened to tell people about the nature of the relationship if the victim didn't give back the gifts and repay him for the financial support.
He later told police he hoped his threats would "rekindle the relationship".
Judge Davidson said he had little doubt the offending was driven by "hurt and raw emotion", but noted it was "significantly damaging" to the victim.
At an earlier hearing, the victim read his impact statement to the court, saying the defendant's offending came at a time where he had just escaped a "cult" and had left everything familiar in his life.
He was struggling with his sexuality, as well as guilt for leaving his family, and was "too trusting".
"I fell into the belief that he could be trusted and as a result I sold my soul to him," he said.
He had to deal with some form of intimidating behaviour every day after the break-up, and would feel anxious at hearing a car pass in the street outside his house.
He eventually felt so unsafe that he moved out of his home, having to give up his pets to do so.
The victim said the defendant "orchestrated a plan to ensnare me".
"He had cemented himself into my life and I couldn't escape.
"Being a slave to the cult I was brought up in, I became a slave to one person."
He said he had still never experienced "normal life".
"2013 should have been the year when I started living and [the defendant] took that from me."
At the sentencing today, defence lawyer Val Nisbet said his client "deeply regrets" what he'd done.
"He acknowledges he stupidly got carried away with what he thought was betrayal," Nisbet said.
He said the defendant had had a "very successful business life" and carried a good reputation in the community.
In sentencing the man, Judge Davidson allowed discounts for the defendant's guilty plea and his previous good character.
Aggravating features included the position of control and power the defendant "unquestionably" held in the relationship, the vulnerability of the victim, the repetitive and persistent nature of the offending, and the damage to the victim.
He sentenced him to six months of home detention and ordered him to pay emotional harm reparation of $3000.
He granted permanent name suppression for the defendant on the grounds he was at risk of suicide if his name were to be published.
He also believed publication of the defendant's name would identify the victim.
