I am the doctor who made a mistake, and you are my patient.

You sat in front of me once before and I missed your diagnosis. You sit in front of me again. Anger in your voice, tears in your eyes, as you tell me of the harm I have done to you. Tears are in my eyes too.

Your diagnosis is the sort a GP dreads. Rare. So rare that most GPs will never see a case in their whole career. Insidious, with vague symptoms, hiding in your body until too late. Life-altering, or life-ending. Cases take an average of six months to be diagnosed. Yours took longer.

There were other doctors, other health professionals who saw you after me. But I was the first to miss your diagnosis. I saw you less than one week after your symptoms started. I examined you thoroughly and found nothing that concerned me.

You hand me your anger and your pain. My hands feel empty as I offer my remorse and my apologies in return. It is not enough. How could it be? When I find out you intend to sue, I understand. As you go I feel a piece of my own life slip away with you. I start to dissolve at my desk.

In the days after, I am tearful and withdrawn. The legal letters arrive, and start the long process of investigation. It’s a strange limbo. I wait to hear if medical regulatory bodies wish to do their own enquiries. Will I be able to continue my career? Will my children see my face in the papers? Doctors under investigation by the General Medical Council have a suicide risk 13 times higher than that of the general population. I turn these figures over in my mind, and for the first time I truly understand them. I know this uncertainty can last years.

The rhythms of life anchor me – but while I brush teeth and read stories, you sit behind me. You are my first and last thought each day, my only thought in moments of peace. Family and friends ask what’s wrong, but I cannot share. I feel shame, guilt, sadness and fear. The smell of failure clings to me like smoke. I no longer know who I am. I read textbooks on your diagnosis, and re-read my own notes from our first meeting. In honesty, I struggle to see anything I would change. Somehow that makes it worse.

I know – I knew – myself to be a good doctor. I take time and listen. I am knowledgeable, and I share that knowledge so we can decide together how to care for you. I am the sort of doctor who phones unsolicited after my surgery to check you are OK, who remembers your name and takes a genuine interest in your life.

But a good doctor doesn’t make mistakes. A good doctor doesn’t get sued. I question my every decision. If I made this mistake, how many more have I made? I cannot trust my judgment. I am not enough. I do not know how to return to work, how to look my patients in the eye, but I have no choice.

In the UK a doctor can expect to be sued four times in a 40-year career. When I qualified as a doctor that figure was 0.5 times per career. You are my first, and I pray also my last. I am the doctor who made a mistake, and I no longer know who I am.

If you would like to contribute to our Blood, sweat and tears series about experiences in healthcare, read our guidelines and get in touch by emailing sarah.johnson@theguardian.com