Petros Williams, 37, of Manchester, deliberately chose internet
connection cords to carry out the murders in a "symbolic act of punishment" for her
having used dating websites following their marriage breakdown.
The children's bodies were discovered by their horrified mother, Morongoe Molemohi, who yesterday described the pain of losing her four-year-old daughter Yolanda and two-year-old son Theo as endless.
Williams brought about further distress by filming a "farewell video" of the children in the days before he killed them in which he coaxed them to say "we will miss you mummy" and "bye mummy".
The recording – played to the jury – was labelled "Daddy Yolly Theo Byee The End", with a note attached which read: "Play the video made for your memories, thank you Petros."
Among several notes he left in the flat was one stuck to the computer which read: "Mo, use the internet as much you like. Love Petros."
A noose was tied to the bed near to where Williams slept as he apparently prepared to kill himself but did not have the courage, said the prosecution.
Manchester Crown Court heard the children's mother was ordered out of the home in Whalley Range a week earlier because Williams was enraged she used the family computer to set up trysts with men online.
A jury convicted Zimbabwean Williams of two counts of murder after just 90 minutes of deliberation. He was sentenced to life imprisonment and ordered to serve a minimum of 28 years before he can be considered for parole.
In a statement, Miss Molemohi said: "The circumstances as to how I discovered the children were such as to bring me the most fearful and distressing memories and I will never be able to wipe the image from my mind, nor forget the terrifying, desperate moments when I scrambled to help them.
"I am their mother, I brought them into the world with the unspoken promise that I would always protect them and at the time they needed that the most I could not be there."
She added: "In the months that have passed since the children died, the effect upon my life has been tremendous. I know that it will continue to impact upon me for the rest of my life and I also know that the pain will never go away."
Sentencing Williams, Mr Justice Kenneth Parker said the children were used as "simply instruments" for his jealousy and acts of revenge.
"You wanted to hit back in a way she would never forget," he told the finance officer and postgraduate student.
"You took these lives to destroy a third life."
Williams denied both counts of murder and suggested during the trial that his wife had actually carried out the killings.