We were on a family holiday when I was left alone to play in the hotel pool. Jumping backwards into the water, I cracked my chin on the pool ledge and knocked myself unconscious.

I’m alive today because a man happened to open the door of his villa and see my blood spreading in the water. He dragged me out and pumped my chest until the water spluttered from my mouth.

The next thing I knew, I was in the hospital, Dad looking over me, grinning. “Let the doctor sew you up, my darling,” he said.

I was only five years old. I was a similar age when I wandered into my parents’ bedroom at home in London and spotted my mum’s contraceptive pills in her open make-up bag.

I sat on the floor crunching the pink sugar-coated tablets between my baby teeth. I’d eaten them all before my parents found me.

Gavanndra as a baby in 1975 with her mum Jan

At the hospital, the doctors decided not to pump my stomach, telling my parents the pills had probably done no harm but I might develop faster than my peers. They were right – I started my periods and wore a bra while still at primary school.

These incidents were part of a pattern of benign neglect that shaped my childhood. My dad, Gavin Hodge, was a top hairdresser in a Chelsea salon with many celebrity and aristocratic friends. He was charismatic and incredibly popular – but he was also a heroin addict and a drug dealer.

My mum, Jan Burdette, was a former model and very shy. She was an alcoholic who drank red wine and often slept through the wild parties held at our Chelsea flat.

By the time I was three, I was making my own breakfast because I never knew when my parents would wake up in the morning. There were always countless people sprawled on the living room floor, out of their heads on drugs.

Gavanndra with her dad Gavin and sister Candy

I worried there would be a fire and often got up in the middle of the night, pinching out candles and making sure there were no cigarettes still burning in ashtrays.

I was eight when the police carried out a drugs raid. They ripped open my teddy bears looking for the stash but left empty-handed.

I knew the drugs were hidden in the battery compartment of Dad’s torch but I didn’t tell. Dad had said it was our little secret.

Although my messy home life was completely inappropriate for a young child, it was also filled with love and I was always happy to be at home.

When I was nine, Mum gave up alcohol, taking the Alcoholics Anonymous 12-step programme, and Dad went into rehab, staying clean for four years.

But all that changed when my little sister Candy died.

We’d gone to Tunisia for a holiday in the summer of 1989. I was 14 and Candy was nine. We would sunbathe or walk into the town to visit the dusty market that sold little stuffed camel toys and leather sandals.

Writer Gavanndra hodge, 46, explains how uncovering memories of her little sister helped come to terms with her traumatic past

One night, Mum knocked on my bedroom door. “Candy’s sick,” she told me.

I was surprised. She’d been fine when she went to bed. While Mum went for help, Candy was choking and coughing up blood.

I stood frozen to the spot as Dad scooped Candy into his arms. She went limp and he tried to give her the kiss of life but she was already unconscious.

I remember him howling, begging Candy to be OK. But the doctors couldn’t save my sister and she died that night. They said she had a rare airborne virus that had attacked her organs.

Back home, my parents placed Candy’s things in a box and locked it. At the same time I shut the trauma of Candy’s death deep inside and tried not to think about it.

Mum’s grief was ever-present and she became more and more withdrawn. Dad’s way of coping was to return to drugs.

I was afraid of Mum’s grief so I followed Dad’s lead. Still only 14, I was drinking, smoking, going to nightclubs and doing speed and other drugs, all supplied by Dad.

Gavanndra says she now understand why her dad behaved the way he did

By now he was dealing drugs from his new Knightsbridge salon. At my public school, I was never short of friends who wanted to join me there after classes, drinking and taking drugs in the basement while Dad flirted inappropriately with my friends.

One school mate, Julia, caught his eye. I was furious when I heard him on the phone telling Julia he couldn’t stop thinking about her. When Mum found a love note from Julia to Dad, she threw him out.

Dad and Julia set up home together in a little flat. She was barely 16 while he was in his forties. I missed Dad terribly and visited him often, but I also threw myself into my schoolwork.

Despite still partying, I passed my A levels and went on to study classics at Cambridge University. My career in journalism took off and I met my husband Mike, who I married in 2006.

In 2009, shortly after our daughter Hebe was born, Dad died suddenly. I was devastated to lose him and still miss him, but I felt lucky that he was here to see one of his grandchildren born.

Minna was born two years later. While outwardly everything was perfect, becoming a mother made me question why my parents had behaved as they did. Worst of all, I realised I had no memories at all of Candy.

All I could remember of her was the day she died.

I was interviewing the psychologist Julia Samuel, a bereavement specialist and a good friend of Princess Diana, when I began telling her about Candy’s death. She set me up with a therapist and I started to work through my past and reconnect with my sister.

Gavanndra with dad Gavin on her wedding day

Mum was shocked when I told her I had no memories of Candy. She shared some stories and showed me photos. Later, we unlocked the box that hadn’t been opened since Candy died.

It was full of things my parents had quickly put in there at the height of their grief – the little pink bikini Candy had worn, a doll with pink hair she carried around, a ruler with her name on.

Mum sat on the bed sobbing and I hugged her, crying too. It felt as though life had finally been breathed into my missing memories of Candy.

Telling my daughters about Candy was harder. I didn’t want them to think of Candy and feel afraid, so I told them about a little girl who painted colourful pictures and liked dancing, swimming, pink clothes and sugary things.

We baked a cake for Candy’s birthday, topped with pink frosting. We now do the same every year to celebrate her.

Forgiveness is complicated. I’m still angry about some of the things Dad did but as an adult I can understand the trauma of losing Candy is partly why he behaved as he did. And I can forgive Mum for withdrawing from life after losing her little girl.

It’s sad that I didn’t have a more innocent childhood but it made me the person I am today – and I don’t regret who I am.

I now feel I have my sister back. She lives inside me. She was here all along, waiting. I just had to look at the world in a different way to find her.