Darren Murphy, aged 41, from Dan Desmond Villas, Passage West, had pleaded guilty to the manslaughter of 36-year-old mother of three Olivia Dunlea, but denied her murder.
A jury at the Central Criminal Court sitting in Cork found him guilty of murder. It was his third trial on the same case.
Mr Justice Pat McCarthy imposed the mandatory sentence of life imprisonment.
The victim’s mother, Ann Dunlea, delivered a moving victim impact statement where she held back the tears until the end of it.
She said of Olivia’s three children: “They have suffered enough for a lifetime and will suffer more but one thing is definite — the love of their mother will never be lost. They are the strongest kids I know and are an absolute credit to Olivia.
“The torture for us really is that nothing we can do will shield them from the pain or make it better because grief does not expire.
How do you console a crying child pining for their mother.
Speaking on behalf of Oliva’s three children, Mrs Dunlea said they described her murder as “not fair, it’s really not fair”.
“Losing our mum was losing part of us. Our best friend is gone. Our world has been flipped upside down and nothing is the same. It’s so hard without her and we miss her so much every second of every day.”
As for what Murphy did — stabbing Olivia in the neck and setting fire to her home — Ann Dunlea said: “Our world is shattered and we are truly living our own life sentence sickened by how depraved and disgusting a human being can be.”
During the trial, the jury heard garda interviews with Murphy. During one he told how he was smothering her in a pillow.
“I twisted her head around towards me. She said: ‘What about my kids?’ So I grabbed the knife and stuck it into her. I didn’t open my mouth once I got on her kneeling over her. I stuck it into the back of her neck… twice I think.
It all happened so fast. I don’t know what I was thinking.
Asked when he knew she was dead, Murphy replied, “When I stabbed her in the back of the neck there was no sound out of her after that.”
While Murphy did not get into the witness box in the trial he ended his last garda interview with an apology: “I just want to say sorry. I didn’t mean to kill her. It all just happened so fast.
“I didn’t want to upset any of the family or the kids. I would do anything to take it back but I can’t.”
Murphy had been in custody since his arrest in February 2013.
This was the third trial of the same case. While he had been found guilty of murder on the first occasion, that was overturned on appeal because of the trial judge’s failure to explain fully the legal meaning of the defence of provocation.