My friends called it a boxcar, the tiny cream-colored duplex I rented in Austin 20 years ago, a long rectangle divided by doorways without doors. The oak floors were so old that the finish had long ago worn away. They were filthy. I mopped, but dirt stubbornly remained caked between the slats of wood.

I was in graduate school at the University of Texas, studying to become a psychotherapist. Before that, I had spent many hours volunteering as a suicide hotline counselor. My counseling skills might have helped others, but they did me little good. Depression stalked me, and with it came its cavalry: anxiety, rumination and insomnia.

My mind fixated on exquisitely small flaws, like the dirty floors in my rental. In the weeks after I moved in, I fumed about the landlord’s reneging on her promise to have the floors professionally cleaned, and I hated myself for not demanding it in writing. In turn, I loathed myself for stressing over the dirty floors so much, and for being unable to stop.

Night after night this cycle repeated itself. Finally, I would fall asleep, only to wake up a few hours later bathed in such intense self-hatred that I couldn’t stand my life. And then I would look at the floors and a fresh wave of revulsion washed over me. I felt panic. How could anyone ever love me like this?

My depression was a dark presence that first came when I was 12 years old and revisited often. Finally, at the age of 26, I started taking an antidepressant, and that helped tremendously. Then I started losing hair, an uncommon side effect, so I stopped. My new therapist in Austin, a psychiatrist, wanted me to try a different antidepressant. But my mind already had tricked me into thinking nothing could possibly help, and even if it could, I did not deserve it.

No one knew. On the outside, I functioned well. With my quirky sense of humor, I often made others laugh. I excelled in my classes on counseling and psychopathology. My curiosity and sensitivity drove me to understand as much as I could about the mind, about people’s pain, about how to help others even while I could not help myself.

For months I lived like this, vibrant and sociable in the day, alone and miserable in my head at night. One night, I could not bear it anymore. I knew that the anguish I experienced was limitless. There was, it seemed to me at the time, only one way to extinguish it.

In the quiet of my boxcar house, I wrote a letter to my parents. I apologized for the pain that I brought into their lives, and I assured them that they truly would be better off without me. I felt certain that some months of intense heartbreak would be better than the decades of pain, uncertainty and fear that my continuing existence would inflict on them.

Then I wrote another note with a thick marker: “DO NOT GO INTO MY ROOM. To spare yourself, call 911. I’m so sorry!” Because there was no door to close, I ran packing tape across the doorway and I stuck the note to the tape at eye level, impossible to miss when two friends who had keys to my place would come looking for me.

I write about this now, more than 20 years later, from my office at the University of Denver. As a tenured associate professor in the graduate school of social work, I teach courses on psychotherapy and mental health assessment. A mile down the road, I have a psychotherapy practice. In my research, teaching and clinical practice, I specialize in suicide risk assessment and intervention, making me what is rather clumsily called a “clinical suicidologist.” The website I created and maintain, SpeakingOfSuicide.com, has had 1.5 million visitors in the last three years.

I am passionate about suicide prevention because I know, both from my own experiences and from those of others, how darkness can convince a person that light will never come again. But my passion angers some visitors to my website. They post comments or send me emails condemning my inability to understand the suicidal mind.

One reader wrote, “Please get off your superior ‘I am a happy person’ high horse. For the most part you were born that way.” Another wrote, “Yes, you might have read about mental illness. Sure, you may have a degree in whatever. But if you’ve never had depression or felt suicidal… then you have you have absolutely NO right to write an article.”

Until recently, I have kept my suicidal experiences secret from all but my closest friends and family. I admit that I feel shame, the very shame about mental illness that I try to soothe and challenge in my clients.

In recent years, several high-profile mental health professionals, such as the psychologists Kay Redfield Jamison and Marsha Linehan, have come forward about their personal experiences with mental illness and suicidality. And more and more people who survived suicide’s assault have begun to share their stories in blogs, social media and videos. I have always been too scared to join this conversation. But knowing my silence made me stigma’s accomplice also felt hypocritical.

The openness of others inspires mine now. I still feel scared, but perhaps it can comfort people with mental illness to know that many professionals who appear to sit on a high horse of happiness, in fact, sit with them.

That night in Austin, I believed I would never feel better. Though I did not know exactly how, my suffering clearly was my fault. After I put up the note for my friends, I laid the letter to my parents on my dresser. Beside it were my bank and 401(k) statements and contact information for a few close friends so my parents could alert them to the funeral. I then set into motion what I naïvely thought would be a peaceful death.

But the body fights back. My suicide method involved asphyxiation. As the air diminished, my lungs asserted their neediness. My chest heaved as I struggled to claim oxygen. I instinctively took in every bit of air until there was none left. Soon, my hands started tingling, and I saw only black. Frantically, moving as quickly as I could, I aborted my suicide attempt. Then I took in huge breaths of air, again and again, an apology to my deprived lungs.

Some suicidologists, in explaining why an estimated 90 percent of people who survive a suicide attempt do not go on to die by suicide,/ believe that the suicidal state is one of dissociation. According to this theory, a suicide attempt abruptly brings the person back to their body, connecting the person to the fundamental imperative to survive. This happened to me. In those moments when I had no air to breathe, I realized that I did not want to end my life. I wanted to end the pain, the obsessions, the agitation. I could find ways to do that while also staying alive.

The next morning, I took down the sign warning friends away, called my therapist at her home, and got a new prescription for antidepressants. I started my long journey from suicidal to suicidologist, not only a person with mental illness but also a mental health professional, with all the contradiction, fear, hope and redemption that those two identities entail.