The family of a mother and her young son stabbed to death by her ex-boyfriend said they were "numb with shock".
Rachael Slack, 38, and 23-month-old Auden, were killed by her ex-boyfriend Andrew Cairns, 44, at her home in Holbrook, Derbyshire, on 2 June.
Cairns was also found dead from knife injuries at the house.
Miss Slack's mother Jean and brother Hayden said the family had been left devastated.
In a statement they said: "We were numb with shock when we were told of Rachael's death and that of her lovely son Auden.
"Rachael was a lovely, caring and devoted mother. Intelligent, talented and popular, she had so much to live for, which makes her death so difficult to grasp," they added.
Cairns, the child's father, was detained twice in the week before the killings, once under the Mental Health Act, before he was arrested for threatening to kill Miss Slack, an artist who had lived in Spain.
He was released on police bail and told not to contact Miss Slack, who was three months pregnant by a new boyfriend.
The Independent Police Complaints Commission (IPCC) is investigating how Derbyshire Constabulary handled the case.
His neighbour Phyllis Bodycote, 80, said Cairns, who had severe depression, may have been told that he could no longer see his son.
Mrs Bodycote said he told her: "I am going to see my Auden. I am having my little boy.
"He absolutely idolised his son," she added.