Ice user 'can't believe' she killed a man

An ice addict "can't believe" she drove into and killed a man being sick in the emergency lane of a Melbourne freeway, a court has been told.

Tara Brennan, 29, has pleaded guilty to culpable driving causing death and drug possession after ploughing into 31-year-old Alan Dunlop at more than 80km/h as he was beside a stationary car on the Western Ring Road in May 2016.

After watching Mr Dunlop's family members break down in Victoria's County Court on Tuesday, Brennan offered a "heartfelt" apology through her lawyer.

"She can't believe what she's done. She knows that she's caused immense pain," Robert O'Neill told Judge Duncan Allen.

"She wishes there was something she could do ... she is truly sorry."

Brennan was spotted speeding and swerving between lanes for 20km before slamming into Mr Dunlop's cousin's car in the emergency lane at Sunshine West, trapping the victim underneath her vehicle.

She tested positive to ice, which was also found in her car, and told a woman who stopped to help she'd smoked weed the day before.

The use of cannabis was not linked to the crash.

Mr Dunlop had been travelling with his cousin but the pair stopped so he could be ill.

He died the day before Mother's Day.

"I will always be broken till the day I die," his mother Karen said through tears.

"I often cry myself to sleep. I hate getting up in the morning.

"I feel so heartbroken knowing Alan isn't coming home."

Mr Dunlop's sister, Renee, spoke of her "indescribable" pain of losing "my best friend, my protector, my hero".

Brennan's own tragic circumstances were detailed to the court.

Mr O'Neill said she was repeatedly assaulted as a teenager, and started self-harming and tried to commit suicide.

She did not finish high school and later got into a relationship with an abusive man who introduced her to ice.

The court was told Brennan had been diagnosed with borderline personality disorder, post-traumatic stress disorder, social dysfunction, and anxiety and depression.

Speaking about her ice addiction, Mr O'Neill said "it can only be hoped ... the inevitable incarceration means she can go a long time without using it".

Brennan was remanded in custody and is due to be sentenced on Monday.

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