A man sustained a serious stab wound after the son of the woman he was having sex with "barged" into the room and threw a knife at him.
Brennan Bryan "snapped" after finding his mum in bed with a man in the early hours of August 1 and armed himself with a blade.
The 22-year-old then "hoyed" the knife at the man, causing a stab wound to his abdomen which later required some of his small bowel to be removed.
Go here for the latest reports and live updates from North East courts
Bryan, of West Chilton Terrace, Chilton, Ferryhill, appeared at Durham Crown Court on Monday to be sentenced for wounding.
He pleaded guilty to the charge at a previous hearing.
Kate Barnes, prosecuting, said on July 31, Bryan had been out in Crook drinking with his mum and the man.
At around 2am on August 1, they all went back to the woman's home.
The court heard that the man and Bryan's mum "had sexual intercourse" in the house, before Bryan "barged into the bedroom" and began shouting abuse at her.
Ms Barnes said Bryan was "calling her a s***" and threatened to "stab" the man.
Bryan then left the room, with his mum and the man quickly getting dressed.
But Bryan, who had been drinking and taking cocaine, returned with a knife, which he "hoyed" at the man, causing a wound to his abdomen.
In a victim statement, the man said the wound "totally altered" his life and had an "immense impact".
The court heard that a small portion of his bowel had to be surgically removed, resulting in him having to change his diet, and he won't be able to work until March, next year.
Lewis Kerr, defending, said Bryan had no previous convictions and was a well-thought of labourer who was described in references as "polite" and "respectable".
He said in police interview, Bryan said "something snapped", after discovering his mother in bed with the man.
Recorder Alex Menary jailed Bryan for two years.
For daily news from the North East's courts direct to your inbox, go here to sign up to our free court newsletter
