"One of the last things Eden said to me was she was going back because at least Bradley loves her," she said.
"Her love, forgiveness, kindness and acceptance got her killed."
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Ms Simpson knew those signs because she was a survivor of domestic violence herself, both as a child and later as an adult.
Domestic violence has echoed throughout her life.
She wants her experiences as a victim, mother and survivor to bring lasting change.
Mr Trussell pleaded not guilty to Ms Kennett's murder, with the trial running throughout 2021.
He was sentenced to life in prison in December of the same year after being found guilty.
The three years between her daughter's murder and her killer's sentencing were a "nightmare" for Ms Simpson, who struggled with grieving while also attending the trial.
She said family members and friends of domestic violence victims felt immense pain.
"I already liked to have a drink, but after Eden, that and a pill addiction became a big problem," she said.
"It overtook me. I have no excuse or real reason, it's just the way I figured out how to cope, how to live, because I didn't want to live.
"I thought it was numbing the pain, and it sort of did, but nothing really numbs it, it just suppressed the pain and anger."
Ms Simpson said she had been sober 21 months, something she said was difficult, but "the best thing" she had ever done.
"I feel like I'm grieving all over again which is hard because I'm doing it now the way I was supposed to do it five years ago," she said.
Ms Simpson has started a Facebook page called Let's Talk It with Eden's Mum, where she shares information domestic violence, while also detailing her grief and sobriety.
Last week, she spoke publicly for the first time her daughter's death at an Adelaide rally against domestic violence.
Ms Simpson said she was nervous before walking in front of the crowd.
"I didn't feel like it was what wanted to hear," she said.
"My story was the big situation, but I wasn't talking all these other were talking , so I felt really out of place.
"But I didn't even get a sentence out and the whole crowd was just wow.
"The crowd went off and the support, encouragement and drive was all there in the crowd."
In Mount Gambier, where Ms Kennett was murdered, locals came together on Wednesday for a vigil to remember the victims of domestic violence.
Limestone Coast Family Violence Action Group co-chair Jane Zeitz said regional women were passionate eliminating domestic violence.
"We want to know we're here in support of not only the women who have lost their lives and the families that grieve them," she said.
"But also to other victim-survivors, we're here to support them as well.
Going public with her stories of grief and addiction hasn't been easy for Ms Simpson, but she said it was the reality domestic violence left behind.
"Hardly anyone wants to hear this stuff or talk this stuff," she said.
"Why? Because it hurts, because it's ugly and life is extremely ugly after it.
"We do this because we need to speak for those who cannot speak, like my daughter Eden, and all the women who have lost their lives."
Ms Simpson said urgent government action was needed to address the issue.
"Educate in general, educate the society and make it more spoken ," she said.
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