“I am just absolutely gutted that someone that they trusted and loved could do that to them," he told Nine.

“I don’t know why she did this, it is just a selfish pointless act.

“To be let down like this and to have my children returned back to me in urns, is just the worst feeling I have ever endured."

Mr McLeod, who had been separated from Mrs McLeod for almost two years, said the tragedy was "totally preventable".

Loading

“They were all that I lived for...now I just have nothing," he said.

“I wanna fight to make sure this doesn’t happen to any other kids ever again.

“I know the kids are in heaven now and they are up there causing amuck and they will be waiting for me when my turn’s done."

In the days after her death, friends described Mrs McLeod as a dedicated and loving mother, incapable of killing her four small children.

Family friend Skye Moore told Brisbane Times Mrs McLeod "was a quiet person and she was so caring; if anything happened she would be the first person to help".

"Charmaine adored her children and I never saw her do anything for herself. She would never wear make-up or get her hair or nails done, she spent everything on her kids and they had so much," she said.

"I will always remember her as a dedicated mother and friend. She was really involved with the school and she went to church every weekend, she was just a really kind person."

Other parents at the school where the children attended to described Ms McLeod as a "beautiful person".

"Charmaine, was the first mum at the school to make me feel comfortable [and] kindly show me the hall. She was such a kind soul, always smiling & chatting at school pickups," Kristie Xandy wrote on Facebook.