Miranda Cowley Heller, 59, grew up in New York in a literary and artistic family. She worked as a ghost writer, book doctor and associate editor at Cosmopolitan magazine before becoming senior vice-president and head of drama series at HBO, where she developed shows including The Sopranos and The Wire. Her newly published debut novel, The Paper Palace, is a tense, evocative tale of guilt and forgiveness whose fans include Meg Wolitzer and William Boyd. It pivots on heroine Elle Bishop’s dilemma: to stay with the husband she loves or pursue the life she always imagined sharing with another man, before tragedy intervened. Your novel takes place during a single day on Cape Cod, with flashbacks stretching 50 years into the past. How did you settle on that structure? This is going to sound a bit naff, but when I was a kid, I saw the John Lennon quote about how life is what happens while you’re busy making other plans. I cut it out and put it on my wall. That schism was an initial impetus, and then I’ve always had this notion that we’re all just given one old-fashioned carousel of slides, and those slides are the stories that we tell friends or therapists when we’re explaining ourselves. They add up to who you are, they determine your direction. The scenes from the past are the slides of Elle’s life up to the precipice of the 24 hours. No spoilers here, but is the ending meant to be at all ambiguous? It’s a tiny bit ambiguous. Personally, I have a terrible antipathy for novels that don’t tell you what happens at the end, but the conversation about this actually really pleases me. I didn’t decide who Elle was going to go with until two pages from the end – I had no idea, I just wrote it. For me it was never a choice between two men. That was a way of articulating an idea. The novel is about her journey to the point of being able to make her own choice, to become her complete self, free of the horrible guilt she’s been carrying for decades. How long did it take to write? At one point in my life I started three or four different books, and then stuck them in a drawer. This was one of them. I took it out almost six years ago, so it was a long time in the writing but I’m not one of those ass-in-chair writers. Sometimes I’ll write all day every day, and sometimes weeks will go by. Your grandfather, Malcolm Cowley, was a poet and critic, your husband is a screenwriter, and your sister-in-law is Zoë Heller. Is belonging to such a literary family freeing or inhibiting? I would say completely inhibiting. I remember my father, who’s a book editor, yelling at me when I was 10 about a term paper I’d written. He’d go, “Cut, cut, cut!” That’s the milieu I grew up in. And because there are a lot of writers who are successful in the family, I was like, if I can’t do it well, I’m not going to try. How did you overcome that? I put so much pressure on myself, but what finally broke the dam was writing a lot of poetry. It changed everything for me. I was suddenly writing from a dreamier place, finding out what was buried beneath instead of purposefully digging. That’s why I don’t ever think in advance, I just close my eyes and let the page do it. What did you learn from your work in television? What I took from that chapter in my life was how to write real dialogue. People don’t lead each other in conversation, they often repeat each other. It’s the unsaid, the spaces in between, that are so cool. And of course I visualise everything very filmically. There are some intense sex scenes in the novel. Were you at all wary of writing those? When I was little, my cousin, who’s a literary editor now, and I would write pornographic poetry and stories together. They were really dirty – like, psycho. Gang rapes and iambic pentameters about erect knights. So I think sex scenes never scared me, except that my sons have not yet read the book, and nor has my dad. It’s refreshing to encounter a novel in which a fiftysomething woman is so intensely desired by two pretty decent men. I think women’s sexuality gets deeper, stronger and more interesting as we get older – I mean, hopefully it does! Women above 50 are totally dismissed in so many different ways, but it’s not uncommon for a woman Elle’s age to have two men completely in love with her; it’s just that people don’t seem to write about that. Like Elle’s, your husband is British. Is there a personal dimension to her rants about his way of always making scrambled eggs in a saucepan rather than a frying pan? That is one of my pet peeves. It sticks – I don’t understand why you guys do not understand! Tell me about Cape Cod. The Cape is my place. Coming from a broken family, it was the one place that felt like terra firma for me as a kid. The 70s were, in a weird way, a rather dark time for kids, because our parents – at least as I experienced it – were so out of control. Naked everywhere, joining ashrams, having key parties or whatever. So all the adults were completely neglectful – narcissistic and up their own asses – but it was freedom. We ran around barefoot, we swam in the ocean. Every time I come back, it feels like the opposite of homesickness. I just slot into myself, I’m suddenly inhabiting my body. What’s the last great book you read? Ali Smith’s Autumn is certainly one of them. There was a particular point where I felt like I was writing poetry instead of a story, and then I read Ali Smith and thought: “Anything’s OK.” What book did you last put down without finishing? The God of Small Things by Arundhati Roy. It’s a book I really love, and I’ve carried it everywhere with me, but for some weird reason I’ve never got more than three-quarters of the way through it. It’s annoying sometimes when something’s so well written that you have to go really slowly to savour every line. What are you working on at the moment? HBO bought the rights to the book in an auction, and I’m waiting to hear back from them on a new draft I’ve written of the pilot. It’s going to be a miniseries, so I’m going to be working on that for a bit if it goes forward. The Paper Palace by Miranda Cowley Heller is published by Viking (£14.99). To support the Guardian and Observer order your copy at guardianbookshop.com. Delivery charges may apply