My daughter Kate died at 6.29 am on Christmas Day – 10 minutes before her five-year-old twins, Oscar and Isaac, came out of their room and asked: “Is it morning?” Barely enough time for her husband Billy to hold Kate’s hand and say goodbye before stocking-opening, which, of course, cannot be delayed.

She had a colon cancer that was already advanced when they found it two years ago.

I had filled and then emptied Kate’s red velvet stocking – bought for her first Christmas, 36 years before – to redistribute her presents. But before going to bed on Christmas Eve, I worried about the stuffed stockings for Oscar, Isaac and Billy resting against the banisters while Kate’s hung empty and limp, and went down to re-wrap her presents and stuff her stocking again.

The rest of the day was basically the blackest of black comedy. For the next few hours I moved, disorganised, between touching Kate’s hand, watching the stockings being unwrapped, phoning the GP, asking Kate’s sister Jo to make the boys their promised waffles, phoning undertakers, letting the out-of-hours doctor in to certify the death while putting the turkey in the oven, consulting with the hospice nurse about arrangements, letting in the second nurse to wash Kate, finding clothes and soap and flannel, picking up wrapping paper from the boys frenzied present-opening, and checking the turkey.

At times I leaned against the sittingroom door, uncertain about whether the turkey or the death arrangements should take priority.

Just as I had stuffed her stocking, Billy had wrapped Kate’s presents on Christmas Eve – in the most horrible pink wrapping paper, WH Smith’s last remaining stock – wrapped them so as to declare her still and always present. The boys helped to open them and decide which of Kate’s family and friends they could be given to. They were quite jolly. Five year olds think differently from us. They live right now, in the moment – and if the moment has Minecraft and Lego and Playmobil, then that’s just fine.

Jean Gross with her grandsons Isaac, left, and Oscar.

The undertakers had made me laugh when I’d rung a week or so ago to ask about funeral arrangements over Christmas. Then they’d said in best call-centre voice: “We’re booking right through Christmas week already,” as if it was a show or a hotel room I was after.

On Christmas Day I asked if they could come at 11am to take Kate away. The lady on the phone said that her colleague might have “a viewing” (presumably taking another family to see someone laid out) at that time and they would let me know. The “removal service” would arrive as soon as possible. Were they estate agents or undertakers, I wondered?

Kate called her cancer the Nuisance, and it led us on a merry dance of operations and chemotherapy. We had hopes that some of the treatment would work but there came a time when I realised that there wasn’t going to be any good news, only degrees of bad.

The best of times was the brief period of all-clear scans in the autumn of 2013. But in December that year, the cancer came back with no further hope of a cure. I felt angry. I remember imagining reading out loud Edna St Vincent Millay’s poem, Dirge without Music:

“Down, down, down into the darkness of the grave

Gently they go, the beautiful, the tender, the kind;

Quietly they go, the intelligent, the witty, the brave

I know. But I do not approve.

AND I AM NOT RESIGNED.”

After that there was another year of chemo to try to hold off the further spread of the disease, and side effects, and a hundred different drugs.

Finally, in the last few months, there was the period of what Atul Gawande, the surgeon and writer, in his book Being Mortal, calls the One Damn Thing After Another or ODTAA syndrome. This, he says, “is what the closing phase of modern life often looks like – a mounting series of crises from which medicine can offer only brief and temporary rescue”.

The last two weeks were hard. They don’t tell you about dying, in the colour supplements. John Diamond, Ruth Picardie, Philip Gould – Kate’s cancer canon – they stop writing when they can’t focus any more. So, the unbroadcast pain, the indignities and the long hours of waiting are forgotten, like childbirth.

Indignities first. Actually, the fact that Kate’s bodily functions ended up outsourced to a number of external bags was convenient when she was mostly in bed, towards the end. But earlier, when she was less ill, it seemed unkind that when other lovely mummies were wondering which designer/investment/statement bag to take out with them, Kate’s choices were the large or small catheter bag, and which particular type of stoma bag (known to Kate’s circle as the AbdoBum™). “Mummy can poo into a bag,” noted Oscar and Isaac with interest.

Then, there was pain. These days there shouldn’t be much pain, they said. She’ll just get sleepier and sleepier. Not totally true. Palliative care is wonderful but always seemed a step behind the infinitely clever disease, reacting to each escalation of pain with higher doses or different medication – but only after some hours of sickness and discomfort, and only after summoning help via the tortuous mechanisms of out-of-hours GP services.

I went out one day to take the boys on a playdate, shopping distractedly, and found myself weeping in the car at Somewhere Over the Rainbow on the radio. “Birds fly over the rainbow, why oh why can’t I?” Why can’t she, I thought. And I came back home to the ruins of my daughter.

She had bursts of energy, deciding to come downstairs and sit in her chair for a while, drifting in and out, mostly making sense but with slurred, soft speech. It was lovely, but somehow seeing this almost-Kate made things harder.

Then she became very confused. “Katie doesn’t know what day it is ... she doesn’t know who Jesus was or what praying is ...” I sang to myself, almost as crazy as she was.

Kate and Billy in 2004.

Christmas won’t be spoiled for us for ever. A wise friend of Kate’s, who lost his own wife years ago, told us that because he remembered and thought about her every day the “big” days (anniversaries and Christmas) held no fears. I think he is right.

Kate once said, in relation to a mother’s love for her children, that “worry is love’s currency”. Well, for the first time in two years I don’t wake up worrying how she is. And two years of advance grieving has helped prepare us for today.

It has helped to have the love of family and friends, and the kindness of strangers, the thousands of messages we have received. Newspaper obituaries (I hadn’t realised until now quite how much it helps to have the life of someone you love rounded off in this way).

It helps that we can feel so proud of Kate’s work. She had always been high achieving. In her 20s she worked closely with two prime ministers; at 30 she was CEO of a charity that supported fragile democracies in Africa, hanging out with heads of state and wealthy American philanthropists. There are lots of babies who wouldn’t be alive now without Kate’s work, lots of children being educated, lots of parents able to find work and feed their families.

More than anything, it helps that we have Kate’s book, Late Fragments, written so that her sons may one day discover who she was and what she held dear. If anything good is to come from losing Kate, it will be that book and the effect it has on all who read it. Kate had, as her friend Katy Brand, the actress, said to her, the ability “to choose just the right word – to roll all the words around your head like ball bearings, until the perfect one drops into the hole”. But if not for the cancer, she probably wouldn’t have become a writer – like most high-flying working parents, she wouldn’t have had time.

The last two years taught us the importance of time, of stepping off the treadmill. As Kate writes in her book: “Everything has changed and yet nothing has changed. In other words, the petty frustrations and stupid ambitions and general rushing around have melted away, but the good stuff remains. And it’s better than ever.”

Because of the Nuisance, we became a much closer family. We bridged the distances that grow between parents and their adult children and came to know and admire Kate and Jo, much more than we would have otherwise. We became part of Oscar and Isaac’s daily lives instead of occasional visitors. And we were – and still are – overwhelmed at the way Kate’s friends and our own have responded to her illness.

I’ve learned that there is more love in the world than I ever knew and that perhaps all we need to do is learn to ask for what we need.

• Kate Gross died peacefully at home from colon cancer on 25 December 2014. Kate finished writing her book in September and received finished copies a few weeks before her death. She leaves behind her devoted husband, Billy Boyle, and her five-year-old sons, Isaac and Oscar.

Late Fragments: Everything I Want to Tell You (About This Magnificent Life) by Kate Gross is published by William Collins, £14.99. To order a copy for £11.99, including free UK p&P, go to bookshop.theguardian.com or call 0330 333 6846