An ACT Supreme Court jury in July found John Christopher Walmsley, 36, guilty of aiding and abetting the suicide of the young mother.

The troubled 25-year-old woman, who Walmsley had been dating for about four months, died after taking a lethal cocktail of heroin and prescription drugs on New Year's Day 2011.

A sentencing hearing on Monday heard Walmsley had admitted using heroin and amphetamines to cope with the stress of facing trial.

The admission, which he made to a presentence report author, constituted a breach of his bail conditions not to use drugs.

The author said Walmsley continued to deny a suicide pact had existed, but accepted the woman would still be alive if he had not procured the drugs.

The court heard he had abused heroin for 18-years and was rated a medium to high risk of committing further offences unless he could conquer his drug addiction.

During the trial, jurors heard Walmsley obtained the heroin, was nearby as she wrote a will and suicide note, and prepared the drugs for her use in his Ainslie Village unit.

The court heard the woman only started using after meeting Walmsley.

Walmsley had called triple-0 after waking to find the woman blue, with foam and blood coming from her mouth, and performed CPR until emergency services arrived.

The Crown argued that Walmsley had acted to facilitate and encourage her suicide bid.

But Walmsley denied the charges, arguing he had not intended for either of them to die.

His lawyer, James Sabharwal, said his actions were inconsistent with assisting her suicide.

The woman is survived by her three-year-old daughter, parents and two siblings.

Justice John Burns revoked Walmsley's bail and warned a jail sentence was inevitable.

The judge will hand down his sentence next month.