The mother of six-year-old Jack Adcock has said she is "sickened" that she initially thanked a doctor and agency nurse after his death, now the pair face jail for his manslaughter.
Dr Hadiza Bawa-Garba was found guilty at Nottingham Crown Court on Wednesday of gross negligence which led to the boy's death in February 2011, while nurse Isabel Amaro was convicted of the same charge on Monday.
Nicola Adcock, 41, said she "thought they'd done their best" in trying to treat the youngster, who had Down's syndrome and a known heart condition, after he was admitted to Leicester Royal Infirmary suffering from vomiting and diarrhoea and later developed sepsis.
But the court heard Bawa-Garba failed to recognise that Jack was suffering from septic shock and when he collapsed, she momentarily stopped life-saving treatment after mistakenly believing he was under a "do not resuscitate" order.
Mrs Adcock, of Glen Parva, Leicester, told the Daily Mail: "When we were leaving, and I was thanking them, the doctor was sobbing. She said she was sorry the outcome wasn't different. I felt sorry for her. I thought they'd done their best. You assume that don't you?
"My gratitude sickens me. I thanked them. Now I want to rip their heads off because the truth is they didn't do their best for him. If it hadn't been for them he'd still be here today."
During the trial, the prosecution said Jack died after a series of failings by medical staff, including Bawa-Garba's "failure to discharge her duty" as the responsible doctor.
The court heard that Bawa-Garba had confused Jack with another patient she had treated earlier in the day.
Her error was picked up by a junior doctor after CPR was stopped for around a minute, although prosecutors accepted the break in resuscitation would not have had any effect as Jack was already past the "point of no return".
A jury of six men and six women took five days to find Bawa-Garba, 38, of Leicester, guilty of manslaughter by gross negligence by a majority verdict of 10-2.
Bawa-Garba and Amaro, 47, of Manchester, will be sentenced at a later date.