A woman who was brutally attacked by her estranged husband outside her workplace, escaped death thanks to a colleague who heard her blood-curdling screams.

Milena was pulling into work on August 18, 2015, when her estranged husband Shelden Vaughan ambushed her in the carpark.

When Vaughan pulled Milena from her vehicle, Dr Knox-Haly, heard her desperate screams.

Martha Knox-Haly (pictured) arrived about 10 minutes late to work on August 18, 2015, just in time to see her colleague Milena ambushed by her estranged husband Shelden Vaughan

Dr Knox-Haly said it was simply luck she arrived to work 10 minutes late, at just the right time to run to her friend's aid.

'We were unbelievably lucky with the timing,' Dr Knox-Haly told the Sydney Morning Herald.

'Milena would be dead if it wasn't for that.'

Vaughan stabbed Milena in the head, neck and chest outside her workplace, a community centre near Villawood in south-western Sydney.

Dr Knox-Haly claimed Vaughan turned the knife on her and stabbed her in the skull when she pulled him from her friend.

Dr Knox-Haly claimed Milena was passed out on the road when Vaughan returned to his own car and rammed it into her, crushing her body and head between the two vehicles.

She said she watched helplessly as he reversed his vehicle and rammed her again.

'I saw him crush her head,' Dr Knox-Haly told the Sydney Morning Herald.

Vaughan, an industrial design lecturer at Sydney's University of Technology, was sentenced to a maximum 21 years jail in the Parramatta District Court on Friday, April 27

Vaughan fled the scene in his vehicle, leaving Milena with multiple stab wounds, fractured ribs, shoulder, pelvis and several fractured vertebrae.

Vaughan, an industrial design lecturer at Sydney's University of Technology, was sentenced to a maximum 21 years jail in the Parramatta District Court on Friday, April 27.

He was sentenced on charges of grievous bodily harm with intent to murder Milena, and wounding with intent to cause grievous bodily harm to Dr Knox-Haly.

Vaughan must serve a minimum 14 years behind bars before he will be eligible for parole on August 18, 2029.

For confidential information, counselling or support, people impacted by domestic violence can phone 1800 737 732 or visit www.1800respect.org.au.