Kevin Keast was a supportive husband, an amazing father and a compassionate social worker.

He also struggled with mental illness and heroin addiction. That addiction ultimately killed him.

Kevin's wife, Sarah Keast, told "Good Morning America" that she and Kevin married in 2005. Shortly before their wedding Kevin had his first episode of severe anxiety.

"Now looking back on it with the clarity of time and space," she said, "that's when the cracks started to form."

There was the search for the right therapist, the right medication. There was a suicide attempt, and Kevin spent a week hospitalized. The couple overcame those difficulties and did the predictable things people do after they marry: the bought a house, they focused on their careers.

It was 2008 when Sarah found out her husband was using heroin.

"He had gone into the bedroom and I was down the hall in the bathroom," she recalled. "The bedroom door was a little opened. There was this strange snoring sound, like nothing I had heard before."

She called out to him, but there was no answer. She opened the bedroom door and found him blue in the face and chest. She called 911.

"The paramedics who were resuscitating him asked 'what did you take?' and Kevin answered 'heroin.' That was how I found out," Sarah said.

"Stops and starts"

The next few years were full of stops and starts. Kevin struggled with his addiction, Sarah from the anxiety and worry about his disease and the post-traumatic stress disorder from finding him near death. They separated and reunited. Kevin got help and found a community in Narcotics Anonymous. Sarah said she sought help, too.

They had two daughters -- Brooklyn and Piper. Very few people knew what was happening, Sarah said.

Kevin went through periods of sobriety and relapse.

"There was always an undercurrent of what if?" Sarah said of the periods where her husband wasn't using drugs. She would find paraphernalia around the house, her clue that Kevin had relapsed. Sarah recalled to "GMA" one morning having to dispose of a needle, then pull herself together to go to her corporate job.

The shame that surrounds drug addiction, Sarah said, forces the person struggling into isolation.

"You pull back from therapy, you pull back from seeing friends and talking to your wife," she said. "So you end up alone with the thoughts that you can use just one more time, that no one will know. In isolation that sounds correct, it makes sense. But if you were able to talk about it with someone you would realize no, that isn't a good thought.

"There's no one there to break that compulsive thought pattern of using," she added.

"I thought things were finally on a good track."

In 2016, things were going well for the family. Kevin had started a new job as a social worker in palliative care at a hospital across the street from their daughter's school. He had gotten healthy and found a psychiatrist he really clicked with. His medication was working.

"It was a happy time," Sarah said. "I thought things were finally on a good track."

That summer, Sarah and the two children went to spend two weeks with her parents at their summer cottage, which was their tradition. Because Kevin was still relatively new to his job, he could only join them on weekends.

"I knew something was up," Sarah said of the August weekend her husband came to visit. "We were very disconnected."

As he was leaving, she spotted a track mark on his arm.

"We were having this like whispering fight, the kids were running around, my parents were packing the car," she said. "He denied it. I was filled with anger.

The night, Kevin didn't call to say good night to the girls.

"I barely slept that night," Sarah Keast said.

All her text messages went unanswered. There was no notification they were being read.

"He fell asleep, he went to a movie. But I knew he had died," she said. "I was in a state of cognitive dissonance."

Her mother finally asked when was the last time she had spoken to Kevin. He had not shown up for work in two days.

"My stomach dropped," she said.

Her brother-in-law and sister-in-law had already called the police. For 30 minutes, Sarah said, she paced, crying and screaming. The police found him dead in his home. It was Aug. 9, 2016. Sarah believes he died two days earlier.

"I don't think I said I love you when he left," she said.

Advice from the experts

Devin Reaves, a certified recovery specialist and the executive director of the Pennsylvania Harm Reduction Coalition, told "GMA" that "if a loved one is using opioids, make sure you have the overdose reversal medication Naloxone (Narcan) at home and know how to use it and that they know how to use it."

Seeking out the advice of a medical or clinical professional is crucial.

"Every community has different resources but it’s pivotal you get connected to them. A great conduit to local resources is local professionals," Reaves said.

Dr. Laura Berman, a sex, love and relationship expert and New York Times best-selling author, said it's important for family members to understand it's not their fault.

"There is nothing you did or did not do that can make your partner use or relapse," she said. "In the heat of the moment, your partner may even cast blame upon you, either outright or obliquely, but this is simply gaslighting. It’s a way to make you responsible for their poor choices, but it is not based in reality."

Come out of the shadows and allow them to do the same, Berman noted.

"Millions of Americans struggle with addiction, and millions of partners often feel shame, blame, or isolation as a result of their loved one’s addiction," Berman said. "It is very taboo for people to admit they struggle with these issues, so this will require bravery and vulnerability, but this courage can be what saves you."

She also said to stay hopeful.

"As they say in the recovery community, admitting you -- or your partner, in this case -- has an addiction is the first step," she explained. "But that the second step should be making space in your mind for the possibility that this can change, i.e. 'My partner has an addiction, but I believe they can recover from this condition and our relationship can emerge stronger than before.' It is crucial to set this clear intention, because hopelessness will drain you and your partner’s ability to battle this disease."

The Keast family today

Their daughters are now 8 and 5. Sarah Keast is the sole parent and is dealing with not only her immense grief, but her daughters' too.

"There's a new rhythm now, for the three of us," she said. "But it doesn't get easier, it's just different."

She left her corporate job and is a writer, advocate and a public speaker who gave a TedX talk. She recently started a business called Lost + Found in Toronto, a retail and social hub dedicated to the pursuit of mental wellness.

And while she feels more fulfilled now than she ever did before, she realizes none of this would have happened had Kevin not died.

Keast hopes that by sharing her story she can help people realize that addiction is one part of a person, not the whole of who they are or were. The shame of addiction, she said, keeps people struggling from getting help.

"As a society we don't judge people who seek help for diabetes or cancer," she said. "Addiction and mental illness is a disease. The person is someone's husband, brother or son. We have to look at the whole person. He was my best friend, the person who knew me best in the world and the person with whom I was the most comfortable and felt the safest."