Rowan Baxter killed Ms Clarke, Aaliyah (6), Laianah (4), and Trey (3), when he doused them in petrol and set their car alight in a Brisbane street on Wednesday morning.
He died shortly after stabbing himself in the abdomen with a knife following the attack.
Ms Clarke's mother Suzanne told Channel 9's A Current Affair on Friday night that her daughter first experienced psychological trauma and abuse through the control of her estranged husband, which slowly turned physical, leaving Ms Clarke in fear for her life.
Mrs Clarke was blunt in her assessment of Baxter: "He was evil".
Mrs Clarke said her daughter was "scared to leave" but had been making small steps to move away in recent times.
She said her daughter only last week brought up the idea of organising a will.
The family claims Baxter stalked Ms Clarke through her mobile phone and knew where she was at all times.
"She wasn't allowed to wear bikinis, she works in the fitness industry and wasn't allowed to wear shorts. She had to cover up," Mrs Clarke said.
"In the beginning we thought he was a prude, but in hindsight we know there was more to it than that. He was controlling. It was Rowan's way or the highway."
"She had to grovel and then he would forgive her. She was petrified.
"He was very good at playing the victim. We knew there was no way she could just say, 'I'm going and walk out the door'."
"She said, 'What happens to my babies if he kills me?'"
Ms Clarke's brother Nathaniel said his sister had confided in him, saying it seemed Baxter couldn't handle the success of his partner.
"He was a very jealous and spiteful person," he said.
"He managed to drive a wedge between us ... it was just all manipulated."
Ms Clarke's father Lloyd told ACA he believed Baxter had ambushed Hannah and the children to gain access to the car in Camp Hill.
He said his daughter bravely escaped the car and gave a detailed report to the medical staff on scene with burns covering 97 per cent of her body.
"To the end she fought to make sure if he survived he got punished for doing that to her babies, she was so brave," Mrs Clarke said fighting through tears.
The Clarke family said there had been multiple incidences in which Baxter would take the children hostage and times where he breached the couple's domestic violence order.
They say more needs to be done to ensure victims are better protected from their abusers and are hoping to establish a support system for women suffering at the hands of domestic violence.
"The system's broken," said Nathaniel, adding that Hannah and her three children were "the best humans".
Where to get help:
• Women's Refuge: Free national crisis line operates 24/7 - 0800 refuge or 0800 733 843 www.womensrefuge.org.nz
• Lifeline: 0800 543 354 (available 24/7)
• Suicide Crisis Helpline: 0508 828 865 (0508 TAUTOKO) (available 24/7)
• Youth services: (06) 3555 906
• Youthline: 0800 376 633
• Kidsline: 0800 543 754 (available 24/7)
• Whatsup: 0800 942 8787 (1pm to 11pm)
• Depression helpline: 0800 111 757 (available 24/7)
• Rainbow Youth: (09) 376 4155
• CASPER Suicide Prevention
If it is an emergency and you feel like you or someone else is at risk, call 111.