Zahid Saeed, 30, has spoken publicly for the first time about the death of his son at the hands of Rosdeep Adekoya.
She was charged with murder but pleaded guilty to a reduced charge of culpable homicide and attempting to defeat the ends of justice at the High Court in Edinburgh on Friday.
Mr Saeed said: "She's a demon. She should suffer every day.
"She's not a monster - not even a monster or animal would kill their own child."
Mr Saeed, of Guardbridge, Fife, said that in his opinion justice should be "an eye for an eye".
He added: "But I don't want her to rot in hell, I want her to live for eternity so she can remember what she has done and live with the guilt.
"No parent should ever go through what I went through. I wouldn't wish that on my worst enemy."
Mr Saeed was in court to hear details of how Adekoya, 34, repeatedly beat Mikaeel before stuffing his lifeless body into a suitcase.
She lost her temper and assaulted the toddler after he was repeatedly sick following a family day out at a restaurant in Edinburgh on January 12 this year.
After he died from his injuries at their city home two days later, she wrapped his body in a duvet cover, concealed it in the suitcase and drove 25 miles to Fife to hide it in woodland.
Adekoya, a prisoner in Cornton Vale jail near Stirling, will be sentenced on August 25.