A committal hearing for alleged wife killer Gerard Baden-Clay will continue on Tuesday after his mistress gave emotional evidence about her love for him.

Toni McHugh fought back tears in the Brisbane Magistrates Court on Monday as she spoke of her love for Baden-Clay, and her heartbreak at learning he'd had other mistresses.

She said their relationship continued after his wife Allison was found dead on the banks of a Brisbane creek in April last year.

She said Baden-Clay had told her to "lay low" as police investigated his wife's disappearance, but later advised her to be honest about their relationship.

At one point, he also denied being responsible for Allison's death, Ms McHugh told the court.

Prosecutors are alleging Baden-Clay's affair with Ms McHugh, and financial debt, motivated him to murder his wife.

Investigative accountant Kelly Beckett told the court Baden-Clay owed $1.18 million to family, friends, business associates and banks.

The court has previously heard Allison's death benefits were worth around $975,000.

Baden-Clay told police his wife, and the mother of their three children, failed to return to their Brookfield home after going on a late night walk.