Twenty years ago, I was the other woman in an office affair. 

I'm not proud of it. I was young - barely out of my teens, really - and so dangerously naive I thought what I was doing was empowering.

Looking back, I find my attitude mortifying.

It started when I was 19, working at a small company with just ten staff. I'd just moved out of my family home and was barely scraping together enough for rent and ramen.

Then there was Gavin - early 40s, married, charming, confident in that 'I've been around' sort of way.

His wife was British and often away, either travelling for work or in the UK visiting family. I didn't give her a second thought. She was just a vague concept - as irrelevant to me at the time as owning a home or filing a tax return.

Gavin made me feel seen in a way that felt intoxicating. He brought me lunch, knowing I could not afford it, slipped me cash to buy drinks on Friday nights, and when I said I needed a laptop to study, he loaned me the money - but told me not to tell anyone.

'Just help me with my computer skills,' he said, a wink tucked into every word.

'After that, the affair ramped up. We had sex at work - locked rooms, quickies between meetings' (picture posed by models)

The flirtation grew slowly over a year or two. He'd compliment my legs when I wore skirts, tell me he'd had dreams about me - but only when no one else was around. 

Looking back, I see it for what it was: grooming. But back then? It felt electric. I thought I held the power. I thought I was a grown woman making grown choices.

The first time we had sex was at a housewarming party for my new sharehouse. His wife was overseas, the booze was flowing and the tension between us had been building for months.

We snuck away to my bedroom like teenagers. At first we slipped in there to kiss. Again and again. By the end of the party we went in for a kiss and didn't come out for hours. I felt wild and wanted and so far from the girl who once saved up to buy supermarket-brand tampons.

After that, the affair began in earnest. We had sex at work - locked rooms, quickies between meetings. The sneakiness was a turn-on. Honestly, the sex was like nothing I'd ever known. 

I'd only slept with one boyfriend before Gavin, and it was sweet but vanilla. Gavin unlocked something in me I didn't know existed. I felt sexy, confident, like I was starring in my own late-night TV drama. Gavin introduced me to porn and we tried what we watched. I was levelling up my sex game, week on week.

When he and his wife announced they were expecting a baby, I was momentarily stunned - but we still didn't stop. He kept coming over. And when he started becoming jealous of my weekends out with friends, I didn't see it as a red flag. I saw it as proof I was irresistible.

But things started to sour. His questions about my life away from him became annoying. He'd call and text constantly. My friends started noticing how wound up I was and told me to cut it off. 

'I'm 39 now. Married. Pregnant with our second. And the memories of that affair have come flooding back like a fever dream I can't shake.' (Picture posed by model)

And the truth was, I was starting to find him unattractive. The fantasy was over and the reality underneath was just… sad.

When he told me they were moving back to the UK before the baby arrived, I felt relief. No social media back then meant that when someone left, they really left.

It was like closing a book you were done reading. I moved on. Had fun. Dated. Laughed. Forgot.

Until I didn't.

I'm 39 now. Married. Pregnant with our second. And the memories of that affair have come flooding back like a fever dream I can't shake.

My husband works in a small company - ten staff. Young admin girls. Work drinks. Late-night calls when projects run over.

My husband, in his own way, is a bit like my old boss. He's not a groomer, of course, but he is a charmer. He has that same swagger and confidence. I know other woman must find him attractive. 

And suddenly, I'm her. The wife I never thought about. The one at home, trusting. The one whose husband is laughing with a co-worker, offering her help with her laptop, paying for her drink at Friday knock-offs.

I watch his location like a hawk. If he's five minutes late, my mind spirals. I scroll through his Instagram likes. I re-read old messages to decode his tone and detect lies. I cry in the shower when the anxiety gets too much. I feel insane.

And the thing is, he's never given me a reason not to trust him. He's never made me feel small or ignored or unloved. But I keep waiting for the karma boomerang to come flying back and smash my marriage to bits. 

It's not just fear - it's a belief. A deep, gnawing certainty that I deserve to be cheated on. That my past has poisoned my future.

I haven't told him what I did. I don't know how to. How do you say, 'Hey babe, remember that new intern you mentioned last week? I was her once. And I nearly blew up someone's life without blinking.'

I worry that confessing would only create cracks where there were none. But not confessing is turning me into someone I don't recognise - someone who is paranoid and suspicious and exhausted.

I wish I could go back and shake my 20-year-old self. I want to tell her she's not as powerful as she thinks she is. That real empowerment comes from having integrity. That being desired is not the same as being respected.

I also want to forgive her. Because she didn't know. She was flattered. She was flirty. She thought this older man saw her as an equal. She didn't realise he was taking advantage of her youth, her low pay, her wide-eyed inexperience.

But mostly, I want peace. I want to stop living in fear of a punishment that may never come. I want to stop holding my husband accountable for someone else's mistake. Mine.

So I'm working on it. Therapy. Talking honestly with my closest friends who remind me that marriage isn't supposed to feel like a ticking time bomb. That trust is a choice you make over and over - not because someone's earned it, but because you have chosen not to be ruled by fear.

Maybe one day I'll tell him. Maybe not. But I do know this: shame grows in silence. And I'm not willing to let it rot the thing I've built just because I once was willing to destroy it for somebody else.

•  As told to Rebel Wylie. Elysia Kailey Thorne is a pseudonym.