Darryl Gebien spent years secretly battling an opioid addiction.

A former emergency room doctor in Barrie, Ont., he started with the painkiller Percocet before moving onto fentanyl: a powerful synthetic opioid that has been linked to numerous overdose deaths. Then, in Jan. 2015, a knock on his door would destroy his career, shatter his family -- and save Gebien鈥檚 life.

鈥淚 opened the door up, and of course I was totally scared, but the investigator, he was kind,鈥� Gebien recalled in a candid interview with CTV News. 鈥淭he investigator just said to me, 鈥榊our life is going to change after this day.鈥� And he was certainly right about that.鈥�

In April 2017, after multiple stints in rehab while free on bail, Gebien was sentenced to prison after pleading guilty to trafficking and forging fake prescriptions to feed his habit. Released in December after serving eight months of his two-year sentence, the 48-year-old, who has been clean for the past three years, is now on a crusade to raise awareness about the pains of opioid addiction.

鈥淭he actual real opioid crisis is not just the people who are marginalized (and) on the street,鈥� Gebien said. 鈥淭hat鈥檚 the tip. The actual iceberg itself are the 20-year-olds, the 30-year-olds who are out experimenting, or addicted, living with mom and dad. There鈥檚 construction workers, other manual labourers, doctors, dentists, news anchors -- people from all walks of life.鈥�

Gebien鈥檚 descent into opioid addiction began innocuously when he took Percocet painkillers after a sports injury. It wasn鈥檛 long before he started taking the pills recreationally.

鈥渓 liked it because it was like a happy pill,鈥� he said. 鈥淎fter I started progressing and spiralling and taking it more and more frequently, I didn鈥檛 realize how the addiction had grown quietly, insidiously.鈥�

To battle his growing withdrawal symptoms, Gebien began wearing fentanyl patches while working in the emergency department of Barrie鈥檚 Royal Victoria Hospital. But Gebien鈥檚 addiction quickly surpassed the relief even the patches alone could provide.

鈥淚 had cut it up in small pieces and smoked one small piece of it, and it was just an incredible high,鈥� Gebien said. 鈥淚f I hadn鈥檛 had the tolerance that I had built with the Percocet, I probably would have overdosed and died at that point because it was so strong. But the addict within me absolutely totally enjoyed it because it was just bliss. I craved it. It worked so fast.鈥�

Soon, Gebien was tricking colleagues into giving him the medication he hungered for, even forging the signatures of fellow doctors. In total, he illegally obtained more than 400 fentanyl patches.

鈥淢y judgement and my insight were affected by the drugs that I was using,鈥� Gebien admitted. 鈥淚 was already so stuck in the slavery part of the addiction at this point. The person who made those choices is not me. I look back and I am shocked with my own behavior and I have to live with that.鈥�

Gebien never went to his superiors for help.

鈥淚 didn鈥檛 because I was scared, fearful,鈥� he said. 鈥淚 thought everything would fall apart around me.鈥�

But everything already was falling apart. Gebien鈥檚 marriage had become fraught and work was already filled with intense stresses.

鈥淎ddiction doesn鈥檛 happen in vacuum,鈥� Gebien explained.

When Gebien was finally caught, he was charged with 144 counts of forgery and trafficking in a controlled substance. But more painful than prison and losing his career is the toll his ordeal has caused on his family. His former wife now lives with their children in the Maritimes.

鈥淭he rest of me is recovering, but they鈥檙e growing up and their dad鈥檚 not there,鈥� he said. 鈥淭hat hurts the most.鈥�

Gebien knows that one day, he鈥檒l have to tell them about his struggles with opioids.

鈥淭hey鈥檙e too young to understand, but there will be a day when I鈥檒l sit down and say, 鈥業 need to explain to you what daddy did and what daddy did afterwards and the good that I am trying to do to undo the damage I caused,鈥欌�� he said.

Gebien is now , partaking in speaking sessions across the province to advocate for more addiction treatment facilities. Currently, Gebien says, there is a three- to six-month waiting list, if not longer, to get into rehab -- but when addicts need treatment, Gebien says, they should be able to get it immediately.

鈥淚 thought emergency medicine was my calling,鈥� Gebien said. 鈥淚 never would have predicted in a million years that I would be speaking and advocating for and destigmatizing addiction.鈥�

Later this year, Gebien will also learn if Ontario鈥檚 College of Physicians and Surgeons will allow him to reclaim his licence to practice medicine. If he does, Gebien says there would likely be strict conditions placed on him, such as regular drug testing.

鈥淚 have learned my lesson, my gosh -- I had plenty of time to think about it in jail,鈥� he said. 鈥淚 believe people deserve a second chance, especially if they鈥檙e open and honest and candid and willing to accept responsibility.鈥�

Despite all his agonies, Gebien says a degree of catharsis has come from his coming to terms with his illness.

鈥淪omething happens to somebody when you鈥檝e been dragged through the mud and paid for it,鈥� he said. 鈥淚n the end, there seems to be some sort of clarity that comes out of it鈥� with adversity comes character and sense of purpose and this is why I am here talking to you now.鈥�

With files from CTV News鈥� medical affairs specialist Avis Favaro and producer Elizabeth St. Philip.