Queuing for passport control after arriving at Palma airport for a girls’ holiday, I was suddenly aware of a huge commotion kicking off behind me.

‘You’ve been f***ing sleeping with her husband, haven’t you?’ yelled one woman. ‘Go on admit it!’ This accusation was followed by all sorts of jostling and screeching.

How uncouth, I thought to myself, assuming the foul-mouthed rant must be from a low-rent hen-do who’d had one too many proseccos on the Ryanair flight over.

More fool me. Turning round, I realised with horror the two women being pulled apart by Spanish security guards were in fact my friends Sarah (the accuser) and Jenny (the accused). Standing beside them, looking absolutely bewildered, was our other friend Ellie, whose husband Jenny was being accused of sleeping with.

It was like a scene from a tawdry soap opera and had no place in my normally well-behaved, middle-class friendship group of eight 40-year-olds.

But here it was. As various members of the group waded in to try and calm things down, the argument escalated until more Border Control officers got involved.

Watching the other holidaymakers filing past, watching us with open contempt and amusement, was the most shameful and embarrassing moment of my life.

But how did it come to this? Until then, we’d been a close friendship group, who had known each other since school. I’d been best friends with Sarah since we were four. We were all working mothers with demanding careers; our ranks included a lawyer, an architect and a translator.

Abigail was horrified when her much-anticipated girls' trip to Mallorca kicked off with two of her friends publicly arguing at the airport. (Picture posed by models)

Some of the group had holidayed together previously, but while I’d joined them for weekends in the UK, I preferred to prioritise foreign holidays with my husband and three children.

Yet I’d never heard of any dramas on any of their trips, so when one of the girls, Lucy, suggested over our WhatsApp group that all eight of us should go to Mallorca for five days to celebrate our 40th birthday year, everyone enthusiastically signed up. We had spent weeks planning outfits and excursions – which made the scene in Palma airport even more baffling.

After eventually being allowed through passport control, we travelled to the hotel in two taxis, where the argument picked up again as the drivers offloaded our bags.

‘Why would you say that, Sarah? Of course I haven’t slept with Ellie’s husband!’ Jenny screamed.

Nobody really knew what was happening. The group divided into two factions: One side who blamed for Sarah for detonating her bomb just as the holiday was beginning, while the other side was more concerned about whether there was any truth in it.

I tried to play peacemaker, but emotions were running so high it was almost impossible. Understandably, Ellie looked devastated and confused.

As for Sarah, she didn’t even step foot inside the hotel, heading straight back to the airport without another word. In fact, nobody heard a peep from her for a couple of months after that.

The remaining seven of us tried to salvage the trip, having spent almost £2,000 each on the flights and hotel, but a shadow lingered.

Dinner that first night was painfully awkward as we tiptoed around the subject. But we couldn’t avoid the burning questions we all had, namely why had Sarah said that? Why now, on the very first day of the holiday? And most importantly, had Jenny slept with Ellie’s husband?

'We tried to be normal but the elephant in the room was gargantuan,' she says. (Pictured: The hit HBO series White Lotus, which examines toxic female friendship dynamics)

Ellie called home in tears and, judging by her side of the conversation, her husband Stuart denied everything. She tried to convince us she believed him, but you could tell there were doubts.

Jenny was in knots about how to behave. We tried to be normal but the elephant in the room was gargantuan.

At regular intervals Jenny would protest to whoever would listen that the accusations weren’t true. ‘Sarah is clearly losing her mind!’ she told me. I chose to keep quiet.

Whenever she and Ellie weren’t around the rest of us played detective, replaying previous evenings out and weekends away when we’d all been together as couples, trying to recall any frisson between Jenny and Stuart. No one could think of anything.

It must have been horrendous for Ellie; she and Jenny had been close for years. They had a few heart-to-hearts by the pool, which they kept civil.

I felt especially sorry for Lucy, who had put so much effort into organising the trip, and whose 40th birthday was actually while we were away.

Although we still had a special dinner for her at a beautiful restaurant in Palma, the evening felt tainted.

Frankly, it was a huge relief to board the plane home.

The group has never recovered, especially as, it was later revealed, Sarah had been telling the truth. Jenny had slept with Ellie’s husband – and it wasn’t the only extra-marital fling she’d had either.

It all came out when Jenny’s marriage fell apart a few months later. Despite his betrayal, Ellie has decided to stay with Stuart – for now. I still haven’t got to the bottom of how Sarah knew – and why she chose to drop her bombshell when she did.

As for Jenny, she’s been removed from our WhatsApp group – and our lives.

There have been other girls’ holidays since the ill-fated trip to Palma, but I’ve declined all invitations. Give me a holiday with three overexcited children any day. I’m sure it’s less stressful.

Abigail Robbinson is a pseudonym. Names and identifying details have been changed.

As told to Sadie Nicholas.