Former Afghanistan hostage Joshua Boyle, accused of assaulting now-estranged spouse Caitlan Coleman, portrayed her today as a mentally unstable person prone to fits and violence.

Boyle testified during his assault trial in Ontario court that Coleman had a tempestuous personality and was mercurial at the best of times.

Boyle, 36, has pleaded not guilty to offences against Coleman, including assault, sexual assault and unlawful confinement, as well as a charge of misleading Ottawa police in the hours before he was arrested.

The offences are alleged to have occurred in late 2017, after the couple returned to Canada following five years as captives of Taliban-linked extremists who seized them during a backpacking trip to Asia.

Boyle says that during their tumultuous courtship Coleman would slap and hit him and even claw at his eyes.

He claims Coleman once came at him with a knife because he brought the wrong kind of mayonnaise home from the grocery store.