The Dowlers were also critical of the initial Surrey Police investigation during which chances were missed to catch Levi Bellfield, who went on to murder two more victims.
Milly’s mother Sally welcomed Bellfield’s conviction but said the trial had been a “truly awful experience” for her family.
Milly’s sister Gemma said the day her parents were questioned by Bellfield’s lawyer in court was the “worst day of my life” adding: “It feels like we were the criminals and we were on trial.”
Milly’s father Bob said his family had had to pay “too high a price” for Bellfield’s conviction, saying the trial had been a “mentally scarring process”.
The family spoke outside the Old Bailey after Bellfield’s trial finally ended.
He was convicted on Thursday of abducting and murdering 13-year-old Milly after she walked past his home.
The jury was discharged yesterday without reaching a verdict on a charge of attempting to abduct 11-year-old Rachel Cowles the day before Bellfield snatched Milly in March 2002. There is to be no retrial.
Judge Mr Justice Wilkie said he had referred the case to the Attorney General with a view to taking contempt of court proceedings because of what he termed “deplorable” media coverage in the aftermath of Bellfield’s conviction for Milly’s murder.
It took Milly’s family nine years to get justice, even though her killer had been living 50 yards from where she was last seen in Station Avenue, Walton-on- Thames, Surrey.
But justice came at the price of the Dowler family being “put on trial” in a process Commissioner for Victims and Witnesses Louise Casey condemned as “quite appalling”.
Both Bob Dowler, 59, and his teacher wife Sally, 51, broke down while giving evidence when the defence probed into their lives and suggested their daughter may have run away because she was unhappy.
For Mr Dowler, an IT management consultant, there was the added humiliation of having to admit he had an interest in bondage sex and that police found a ball gag at the family home in Walton Park.
Milly had found a porn magazine with contact numbers for women providing kinky sex nine months before her death, and felt let down by her father, the court heard.
This led to detectives initially considering Mr Dowler as a suspect.
Milly’s sister Gemma said of the Dowlers’ experience in court: “We can’t let this continue.”
She said it was far from an isolated case and she warned that it must be stopped to avoid the risk of rapists and murderers walking the streets because people do not feel able to report crimes or give evidence.
Mr Dowler, standing alongside his wife and daughter, told reporters outside the Old Bailey that his family had paid “too high a price for this conviction”.
He said: “The trial has been a truly horrifying ordeal for my family. We have had to relive all the emotions and thoughts of nine years ago when Milly first went missing and was then found murdered.
“During our questioning my wife and I both felt as though we were on trial.
“The questioning of my wife was particularly cruel and inhuman, resulting in her collapsing after leaving the stand.
“We despair of a justice system which is so loaded in favour of the perpetrator of the crime.”
Surrey chief constable Mark Rowley apologised to the family for mistakes which initially allowed the killer to evade justice.