All it took was a single beer for Murray Shaw's life to unravel.

The moment came on a bike holiday in January 2016 in San Diego while he was with some friends from the Vancouver area.

After almost 20 years sober, the community college instructor from New Westminster, B.C., cracked open a cold one at the end of a long ride.

Fourteen months later, he died alone in a hotel room in Vancouver's Downtown Eastside.

Fentanyl overdose was the coroner's conclusion.

"He wasn't making a choice with a rational mind. He was depressed and he was battling this impulse to use," said his wife, Sasha Wood, who offered to tell her husband's story to CBC News in the hopes it might help other families dealing with substance abuse issues.

So far in 2017, fentanyl is believed to be linked to more than 170 deaths in the city of Vancouver alone. (Chris Corday/CBC)

Fentanyl has become a scourge across the country, but B.C. has been hit the hardest: an average of four people have died of a drug overdose every day in 2017.

Wood said the events that led to Shaw's death illustrate much that's wrong with how the Canadian health-care system treats those with an addiction.

'I just thought he could stop'

Shaw had problems with alcohol in his 20s and got into trouble with the law. But Wood, 49, says he sought treatment and turned his life around.

He stopped drinking completely, went to university and worked toward a PhD.

At the time of his death, Shaw was 57 years old. He was an avid athlete and a respected faculty member in the sociology department at Douglas College.

"He loved to ski at Whistler. He got into biking and racing and he just loved his life," she said from the couple's home, where happy photos of outdoor holidays line the walls.

But Wood says everything fell apart on that bike trip. One beer led to several and then to hard liquor. Wood says she had to fly down and bring him back to Canada.

Shaw was an avid athlete and competitive cyclist. He relapsed during a biking trip in California. (Sasha Wood)

"At first, I just thought he could stop, because he said he could. And then I recognized how unwell he was and how he couldn't stop on his own."

Shaw told administrators at Douglas College about his relapse, and his health plan paid for two expensive trips to rehabilitation programs.

But Wood says shame and guilt played into his fears of losing his job and embarrassing his family. She now acknowledges he stopped treatment too early.

"He was having this struggle. Every day he was in turmoil and fear."

'He felt so much guilt'

Colleagues at Douglas College said they knew Shaw was having trouble with something at home, but fellow sociologist Bill Angelbeck said no one suspected drug use was the issue.

"He was withdrawn and reserved and I just thought to give him some space," said Angelbeck.

Looking back at it, Angelbeck says that was a mistake.

"I just wished I had the conversation. We could have talked about it."

In the months that followed, Wood says, Shaw's addiction turned from drinking to hard drugs, which brought him to Vancouver's Downtown Eastside — ground zero in the fentanyl crisis.

That's where he met Dale Brown. They both came from Sarnia, Ont., and the connection helped spark a friendship.

Dale Brown occasionally shared heroin with Shaw and was one of the last people to see him alive. (Glen Kugelstadt/CBC)

The two men would sometimes use drugs together, and Brown said he could see his friend's life was being ripped apart by his addiction.

"He realized he was in a relapse and he felt like he was just drowning in pressure," said Brown, who was one of the last people to see Shaw alive. "He felt so much guilt about letting his wife down."

'The saddest moment of my life'

One day in late March, Shaw checked in to Room 406 of the Patricia Hotel.

When he didn't come home that night, Wood called police.

Two hours later, an officer knocked on her door and broke the awful news. Shaw had been found dead.

Shaw struggled with alcohol addiction but had been clean for 20 years, earned a PhD and was a sociology instructor at Douglas College in New Westminster, B.C. (Sasha Wood)

"It was the saddest moment in my life. I was in shock. I didn't want to believe it," Wood said. "Just the thought that he was alone, by himself in a hotel when he died, suffering and probably feeling very guilty."

She says a lot of it has to do with how the health-care system treats addiction.

"He was fighting something much more powerful than he was — it was like his brain was hijacked," she said.

"It's not a physical health issue, it's a mental health issue. It's something I think society has trouble grasping."

Shaw was found dead, alone in room 406 of the budget Patricia Hotel on Vancouver's East Hastings Street. (Chris Corday/CBC)

Wood says, even if addicts do get treated, families often don't get any direction on how to support them post-treatment — what behaviours to look for, how to deal with a relapse, how much to trust them and how to balance encouragement and enforcement.

When her husband came home from hospital visits and treatment programs, she had no idea how to care for him properly, she said.

"It had me really beaten down. I really recognize that family members are really affected by the trauma."

'We know what's needed but it doesn't exist'

One of the country's leading experts on addiction says Wood's experience is typical of many other families.

"The resources aren't there," said Dr. Evan Wood. "The resources go into ambulances chasing people around, police chasing people around … I could go on and on."

St. Paul's Hospital in Vancouver, where Dr. Wood practises, dealt with over 5,000 emergency overdoses in 2016 — a number that is overwhelming the ability of first responders to cope.

Dr. Evan Wood, director of the B.C. Centre on Substance Use, says he doesn't think Canada has yet hit rock-bottom in the opioid crisis. (Chris Corday/CBC)

"We are hemorrhaging money into the health-care system rather than having a system of care [for addictions] that could improve communities and families," he told CBC News.

Dr. Wood said there is not enough focus on preventing people with addictions from relapsing and ending up back in the ER.

"To catch people whether they are early on or falling off a cliff. We know what's needed but it doesn't exist."

Sasha Wood says she's been comforted by the kind words and support from Shaw's colleagues, but she's haunted by what she considers missed opportunities to save her husband's life.