During his final two years, his anxiety about work increased. He slept more than usual and lost weight. He also lost his spark and joy. We saw our couples’ therapist more often, and she helped us navigate our issues and helped us better understand how to manage his disease. I cut expenses to help alleviate his worry.

The weekend before he died, he couldn’t get out of bed. I asked if I needed to take him to the hospital, and he said no. On Saturday I called his psychiatrist, who spoke with him and made an appointment for Tuesday. He died on Monday. I found out afterward that one of the last things he told his psychiatrist was that he felt his intellect was going, and that he was a failure, just like his dad.

When I compare photos from our son’s bar mitzvah in 2012 and our daughter’s bat mitzvah in 2015, I can see the change in my husband’s eyes and in his thin frame. His face lacked color, his smile was forced, and he didn’t look as if he were all there; he looked like someone dying. That was nearly a year before his suicide. My rabbi said that my husband, like a dying cancer patient, had been in hospice care. We just didn’t realize it.

[Read more: What to Say (and Not Say) to Someone Grieving a Suicide]

When he died, my husband was still in treatment, as he had been for 20 years. After his first suicide attempt, he successfully went through intensive treatment of his disease — comparable to the radiation and chemotherapy phase of cancer treatment — and his disease went into remission. He did everything a cancer patient would have done to prevent a recurrence: He faithfully checked for the earliest signs of the disease returning, and minimized his risk factors. His psychiatrist adjusted his medications as needed and provided excellent medical care, support and counseling. But in the end, everything my husband was doing somehow couldn’t help anymore. He was still on the medication that had worked for so many years, but now it was failing.

Just as cancer may go into remission but still kill in the end, depression is a chronic disease that may ultimately prove fatal even with state-of-the-art care and resources. Not all cancers can be cured. Nor can all depressions. With the strong foundation of our love and his excellent care, my husband had almost 20 years of remission before succumbing to his disease.

I know that depression is not cancer, but both diseases can be insidious. With cancer we see uncontrolled cellular division and the spread of cancer cells throughout the body, and in depression we see the workings of neurotransmitters and how molecules affect mood. Researchers believe each is the result of genetic and environmental factors, and with my husband’s family background of mental illness and an abusive childhood, it’s not hard to see why he was sick.

Suicide is how my husband died, but depression was what killed him. His suicide was not a rational, intentional act, but a complication and fatal outcome of a very complex and difficult disease. Just as cancer invades the body, depression invades the psyche. And just as the surviving family members of patients with incurable cancers know that they were powerless to stop the progression of the disease, so are the survivors of a person with depression who dies by suicide.