The last thing my mother, Eryl, told me on her deathbed was to shut up. I laughed, not because the command didn’t hurt, but because she’d been telling me to be quiet, in one way or another, my whole life. For someone who only ever wanted to be a writer, this has been a serious problem.

I was brought up in the small Welsh-speaking community of 1960s and 70s Cardiff, a dispersed village within the city. Eryl was a highly respected English teacher and we were immersed in books from childhood. Every time I meet one of Eryl’s former pupils they rave, rightly, about her ability to bring set texts to life. She was known to be strict but fair, didn’t have favourites and treated everybody the same.

In the family, though, it was a different story. I was a bright child who did well at school, and yet the least misstep at home would send Eryl into a rage at me. I drew the lightning like a rod and was forever being accused of being disobedient or over-sensitive (two requirements for a writer), when all I was doing was being a normal child. These devastating attacks grew in intensity during my teens and have seriously damaged my sense of self, leaving me devoid of self-confidence and feeling that I’m intrinsically wrong in the world.

Within the spectrum of emotional abuse – the squashing of independence, the subordination of one’s life to another, the gaslighting – writing became the arena of one of our biggest fights. I began writing poetry at the age of seven. During a wet Easter holiday, I composed a rhyming epic about rain. Here was something Eryl approved of. She promptly “corrected” my work in red ink, like the teacher she was. All that was required was uncritical approval, but, rather than trust me to develop at my own pace, Eryl stepped in with “encouragement”. My writing was regarded as a joint venture.

We entered the regular children’s poetry competitions run in Y Cymro, the Welsh weekly national newspaper, and often won. I’d start a poem and Eryl would “improve” it. I could see that this co-writing was making me a better poet and I learned a huge amount from my mother. While this was happening, I basked in Eryl’s positive regard. Would-be writers can be dangerous, if they trespass on other people’s creativity. Eryl was undoubtedly a good writer and would have been far happier if she’d been able to pursue her own work but she concentrated instead on pushing my endeavours.

A large part of the Welsh-language literature scene is based on the competitive model of the eisteddfod. As I grew older and began to enter – and win – national eisteddfod competitions my unease grew about this forced collaboration with my mother. I hated the attention winning brought, it made me feel like a freak, which no teenager wants (though I still loved writing). It purchased peace at home but left me deeply embarrassed, as I felt I was cheating. Eventually, when I was 17, I rebelled against the coercion and refused to write at all. “Our relationship will never be the same,” Eryl said, after a whole Christmas holiday of emotional blackmail and sulking. In my opinion, that could only be a good thing.

Without writing, I found myself emotionally and morally blind, unable to use words in patterns to work out what I thought and felt about an issue. My solution after college was to go to America to see if I could be a poet on my own terms, at both Harvard and Columbia universities. It took me the longest time to be able to hear my own internal voice. I could no longer outsource my own value to an intimate, if abusive, critic. I remember walking around New York with a knot in my stomach, caused by the words that I didn’t yet have the skills to wield. Eryl disapproved of my writing now that it was independent of her but, I felt, was also envious of it.

As well as defying my actual mother, I wanted to find out if I could survive the act of cultural disloyalty by writing in English. What does a poet owe her mother tongue? I began to interrogate the shadow side of the mother image for language acquisition. This was done in code, but Eryl noticed and minded. The first poems I published included “Welsh was the mother tongue, English was his”, a fiction based on how my father taught me “the thin language” (as English is known in Welsh) while my mother was in hospital giving birth to my sister. I found that the profound discomfort I felt, living between two languages, was now a fertile subject and gave rise to a wild mirth in me. Gradually I found that I could stand by, rather than cringe at the poems I wrote.

As soon as I stopped caring what anybody else thought of my writing, things began to go well. I felt that I didn’t need to choose between Welsh and English poetry but could do both, which is what comes naturally to me. This made the work of being National Poet of Wales a pleasure, as if both parts of my brain were speaking to each other. I worried about fulfilling the job with integrity but not about my right to speak. Once you’ve lost that, and have fought as hard as I have to regain it, then nothing is ever as artistically frightening again.

It’s clear that Eryl herself had been emotionally abused as a child. I always felt deep pity for my mother as she struggled with the black depressions that would take her to bed for days at a time. I longed for her to be happy and I would have done anything to make that possible. Or almost anything.

My background has left me hugely conflicted about my art. I know that poetry isn’t all benign therapy. As well as being a cathartic form of self-expression, it can also give insights that a person isn’t ready, psychologically, to handle. If it can heal, art can also harm. In 2005, just after being appointed the first National Poet of Wales, I was at the Hay festival. A fellow poet congratulated me genuinely, then asked: “Why are you wincing?”. The truth was, I was feeling an old blow, confusing praise with being under my mother’s thumb.

There are massive costs to having been emotionally abused and you never fully recover. No matter what I achieve, self-loathing and shame still come from nowhere, leaving me unable to look the world in the eye. I’ve gradually had to give up the narcotics of alcoholism and compulsive overeating.

However, there are some useful side-effects. Now I can spot emotional coercion a mile away. I trust nobody’s opinion about my work other than my own. This is sometimes lonely, but it beats having my artistic initiative hijacked by anybody else. I resist conformity and all groupthink. I’m highly suspicious of how language pushes us to say things we don’t mean. Having been repeatedly annihilated by my mother in childhood, I’m resilient as hell and nothing puts me off practising my writing.

As an adult, I chose to keep in touch with my parents and looked after them at the end of their lives. I’m well aware of how horrified Eryl would be by my memoir, Nightshade Mother and that, in depicting my relationship with her, I’m breaking a taboo about the benevolence of mothers. But the writing is as honest and as fair as I can make it. This sustained act of attention, over years, in all kinds of emotional states, good years, bad years … is the best kind of love I can offer Eryl: the drive to understand and be truthful.

If that isn’t a good artistic manifesto, I don’t know what is.