Slingerland, 91, was found guilty in May of indecently assaulting four young boys when he was a family doctor in rural Mount Albert.
Robert Willitts, 54, is one of four men who said they were assaulted between 1959 and 1970 by Slingerland--when they were between the ages of 5 and 13.
Willitts delivered a victim impact statement Monday and reprimanded Slingerland's supporters for not listening to the four victims when they came forward.
"Shame on you for living in your ignorant and safe cocoon," Robert Willitts, 54, said to three dozen of Slingerland's supporters in a Newmarket court. "Open your eyes and lift up your heads."
Willitts' brother, William, 56, said he has spent thousands of dollars on counseling to help him cope with the abuse.
"I measured my worth by the low value that Slingerland placed upon me," William Willitts said..
Slingerland, who was also a Cub Scout volunteer, sat stone-faced throughout the proceeding.
He remains free on bail and the sentencing hearing will continue Oct. 23.