Glen Cassidy shot Michael Caposiena in the head, killing him at his Melbourne home in March 2016, before himself dying of stab wounds at the scene.
Edmunds, 34, is standing trial for murder. Prosecutors allege she directed, encouraged or assisted Mr Cassidy to kill Mr Caposiena over a child custody dispute.
Ellen Edmunds said her daughter was very distraught when she called her after midnight to tell her Mr Cassidy and Mr Caposiena were dead.
The day after the men died she drove to her daughter's home in Shepparton to comfort her, she told the Victorian Supreme Court on Friday.
"She was very emotional, crying, sobbing. I think she was saying was that it was all her fault, none of this should have happened, Glen wasn't supposed to die," Ms Edmunds said.
"Another comment she made was that all of her troubles were over."
Over a cup of tea, Edmunds allegedly told her mother she "wouldn't have to worry about child custody issues anymore".
Jurors were shown a text message sent from Mr Cassidy's phone, which Edmunds had forwarded to her mother.
"If I get caught, I want them to know you have nothing at all to do with this. This is my choice, my decision," the text said.
Prosecutors claim Edmunds sent the message to herself from Mr Cassidy's phone.
Ms Edmunds said she did not believe the text was written by Mr Cassidy because he could not spell properly.
The court heard the mother and daughter had become estranged after 2014, when Edmunds reconnected with her biological father.
But Ms Edmunds said there was still trust between the two at the time of the murder and that her daughter asked her to visit a funeral home with her to help organise Mr Cassidy's service.
The trial is continuing.
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