Hannah's brother also spoke out last month of his horror at how his sister and her children suffered at the hands of her evil husband Rowan Baxter.
Hannah, Laianah, four, Aaliyah, six, and Trey, three, were set on fire in a car in Camp Hill, Brisbane, by the former NRL player. Baxter died from self-inflicted stab wounds.
In an interview with 7.30, her brother, Nathaniel Clarke, said: "It wasn't quick. It was planned and executed ... He couldn't even do it quick. That's the worst thing. He made them suffer, and her."
Mr Clarke said "he seemed at the start like a good bloke," but his brother-in-law's controlling nature was more obvious in the last two or three years.
"He was the type of person that had to win everything, had to be the best at everything, really didn't like when he wasn't," he said.
"He had to control every moment he was in. To be one of those people, it does make you selfish, and that was it. It was all about him."
Hannah’s parents, Lloyd and Sue Clarke, previously opened up about how Hannah tried to escape the “monster” who ended her life.
“She said to me [the week before she died]: 'Mum should I do a will? What happens to my babies if he kills me?',” Sue told A Current Affair. “Because he’ll go to jail for murder, who gets my children?”
Sue revealed Baxter had spoken to his children over the phone and had been crying, the night before he killed them.
“She hung up or the children hung up she said to me, ‘Mum I feel so bad for him’,” Sue said, adding that Baxter was good at playing the victim.
Lloyd, Sue and Nat revealed Baxter had created a wedge between them and Hannah and controlled her - going so far as to track her phone conversations.
“He was a very jealous and spiteful person,” Hannah’s brother Nat said.
A domestic violence order had been taken out against him after he took Laianah on Boxing Day and kept her from the rest of her family for four days.
“He was evil,” Sue said.
Two or three weeks before Hannah's murder, Baxter breached the order after printing out A4 size images of Hannah in her underwear and plastering them all over her car. After she confronted him, Baxter twisted her arm up behind her back, before Sue went racing out and screamed at him, but he simply drove off.
“She was not allowed to wear shorts. She was big in the fitness industry. She’s a crossfiter - she had to do competitions in tights,” Sue said.
“She wasn’t allowed to walk off the beach in bikinis. She had to cover up.”
Hannah had suffered burns to 97 per cent of her body in the attack and died hours after her children.
But before she passed away the mum-of-three gave a detailed report to first responders about what had happened.
Her family are still trying to come to terms with the massive loss, but hope her legacy can live on.