Russell Owen, 44, was jailed on Wednesday after pleading guilty to charges of false imprisonment, intentionally causing injury, sexual assault and assault.

"You put these people through a prolonged and traumatic ordeal which was calculated to hurt and to cow them such that it continues to affect them to this day, " County Court Judge Michael O'Connell said.

Owen admitted he held the man and woman, who cannot be named, captive at his Heyfield house, east of Melbourne, from December 24 to 26 in 2017.

He suspected the woman, who he had been dating, was having an affair with her friend, despite their denials.

The pair had been drinking and playing pool with Owen at his house on Christmas Eve when he proposed a threesome, the court was told.

But the man said he wanted to remain faithful to his fiancee.

Owen flew into a rage and grabbed him by the throat.

He bashed the man, threatened him with a knife and forced him to crawl to the bathroom and into the bathtub, where he was tied up.

While the woman yelled for Owen to stop, he forced her into the bathtub, kicked her between the legs and smashed her in the face with a broom handle.

He forced both to stay in the bath for hours. They were interrogated about what they had been doing together days before.

After moving into the bedroom Owen forced the man to watch pornography and sexually assaulted him as the woman screamed.

Owen threatened the man's family if he told them what happened, before freeing him.

Owen continued to hold the woman captive, threatening her with a homemade taser, holding it to her neck.

"She was understandably terrified," Judge O'Connell said.

On Boxing Day he repeatedly abused her and said if he went to jail it would be her fault.

Owen was arrested on December 28, after the man and his family went to the police.

The judge said the attack was prolonged and was "cruel, humiliating and degrading".

Owen was sentenced to serve five years behind bars, with a three-year non parole period.

Australian Associated Press