Alexander Gray, from Roundhay, was one of seven boys abused by Leeds Grammar School classics teacher Christopher Slater over a 16-year period between 1976 and 1992.
Mr Gray, now aged 37, was an academically gifted 14-year-old when he was sexually assaulted.
He went off the rails following the abuse, his grades nose-dived and he later becoming involved in drugs and crime.
Speaking after 68-year-old Slater was jailed for four years and four months, Mr Gray, who has waived his right to anonymity, compared the effects of the abuse to post-traumatic stress.
He said: “The impact was massive. I went from a full scholarship and swimming for Leeds to using cannabis and drinking to excess. It was a coping mechanism. I was self-medicating.
“School was tough anyway, but then on top of everything else I had this to contend with - this pervert following me around.
“You end up blaming yourself because you’re a child. I didn’t think anyone would believe me.
“I didn’t tell my mum because that’s the worst thing a parent can hear. I thought I could carry it around with me, then leave school and get a job and then move on.
“Soon after I left school I started using heroin. Before this happened I was clearly not on the path to being a heroin addict.
“You have to take personal responsibility for your actions, but I don’t think my life would have taken the path it has taken if it hadn’t happened.
“I have school friends who are driving around in Ferraris and living in big houses. There’s no reason why it couldn’t have been the same for me.”
Mr Gray was invited by Slater to attend a clandestine “smoking club”. It was there that he was shown pornographic images and assaulted.
He finally told police what had happened two years ago after news of Jimmy Savile’s crimes was reported.
As a result of a subsequent appeal, police investigated several other claims.
Ex-teacher Slater, now 68, was jailed for four years and four months at Leeds Crown Court after admitting seven charges of indecent assault.
Mr Gray, who waived his right to anonymity, urged other victims to follow his lead.
He said: “No matter how embarrassed they are or how ashamed they feel, it’s not their fault.
“It’s never too late to come forward and this proves it.”
This week’s court case was not the first time Slater, now of Glamis Avenue, Heywood, Lancashire, had been prosecuted for child sex crimes.
In 2000 he was jailed for three-and-a-half years for grooming and performing sex acts on an 11 year-old-boy.
Mr Gray said he felt “pity” for Slater.
“He must be messed up, he must be broken in some way to function like that,” he said.
“But no matter how charitable I try to be, the point is that he acted on his thoughts.
“He didn’t have to, but he did so repeatedly and that’s just so wrong.”