Erica Barley was in many ways a normal mum-of-two.

She cooked homemade meals for her two kids, kept the house in order and adored her children.

But the young mum had a devastating secret - she was addicted to heroin.

She shared her story from prison, where she is serving time for the death of her 14-month-old daughter Annabella.

Addicted at 17

"I failed her,'' she told 10TV.

“I was a drug addict. But I didn't ... daily life, they didn't know that. I was able to keep it well-hidden. but I loved my kids. Our mornings, first thing in the morning, we cooked breakfast together. We did normal things. We'd go to the pool, they would play together, watch cartoons, we had a normal life."

Erica would go out at night to source her drugs. She thought she needed them to be able to be a good mother.

"I really believed that I had to keep using so that I could be a good mum. I know that is outrageous and ridiculous, but that is what I believed," she said.

Erica became an addict at age 17. When she was in a car accident she was prescribed the painkiller Percocet. That led to her needing more pills, and oxycontin came next. But when that drug became too expensive she turned to heroin.

She convinced herself and everyone around her that she was functioning.

People thought she was doing OK

“That I had this under control. I was a functioning addict, so I was able to convince the people who knew me the most that I was doing okay.

"This is the process of the life of an addict. You lie, manipulate, and my biggest manipulation was trying to convince everyone that I was clean and sober."

World came crashing down

But on May 27, 2015, her world came crashing down.

“At the time, I really never thought that I was putting my daughter in risk at all by bringing her to a drug house to get drugs," she told 10TV.

"She was asleep in her car seat. She's safe. Everything's fine,” Erica said.

Taken into the drug house

Erica and a friend took Annabella into the house for 10 minutes while they bought heroin. By the time they got back to the car Annabella's lips were blue. She was rushed to hospital but could not be saved.

A coroner's report found the little girl had died of exposure to heroin and fentanyl.

"I just remember dropping to my knees and it was like losing her all over again,” Erica said of learning the reason for her daughter's death. “Because not only did I lose her, but it was because of me she wasn't here anymore."

Five-year jail term

Erica pleaded guilty to Involuntary Manslaughter and was sentenced to five years in prison.

She is sharing her story to warn others of the devastation of drug addiction.

“If I wasn't a heroin addict, she would still be here," she said.

"It doesn't matter who else was there that day. It doesn't matter who knew I was using. At the end of the day, had I not been addicted to heroin, and taken my daughter to that house, she would still be here. So yes, I'm responsible for her death. Can you live with that? Because I don't want you to have to."