This story is part of the May 26 edition of Sunday Life. See all 14 stories . I know very few details about my dad.

I know his name (the one intentionally left off my birth certificate), the school he attended, and how he and my mother met. I know they were in a seven-year-long relationship, and that for as long as my mother knew him he was – and, as far as I am aware, still is – married to another woman. And I know that with this wife he shares a son who is just one week younger than me.

For my dad, keeping me a secret might be necessary to hide his betrayal. But I no longer wish to be a secret. Two pieces of information I know about my father are the only ones he ever shared with me personally, seven years ago.

The first was his brief medical history, and the second was a warning: that if I ever shared my existence with his wife or son, he would never speak to me again. Nearly 15 years before I was given this warning, my father had abruptly and without notice stopped calling our home phone or sending my mother and me holiday and birthday cards, as he had done every year up to that point. I had just turned 18 and it was as if he had vanished into thin air or, from my mum’s perspective, died – a presumption that, at the time, I was ambivalent about.

For years I had held resentment about a man who proclaimed himself to be my dad, or at least my “pal” – the term he used when referring to himself on my birthday cards – yet whose actions showed the opposite. Inten.