A jilted husband who bashed his brother with a shovel after he discovered him having sex with his wife in the back of a car has been sentenced to time behind bars.

The Burnie Supreme Court heard David McCulloch became suspicious when he couldn't get in contact with his wife of six years, who he shares four children with, earlier this year on March 28.

Later that day, the 41-year-old Devonport man found his wife and his brother having sex in the back of a parked car while his mother sat in the front seat.