'Do you know why the other mums don’t like me?’ my friend, Jill, asked bluntly. Her tone was a sorry mix of upset and indignation.

We were having coffee after attending a special parents’ assembly at our children’s school. Her question put me on the spot, although I wasn’t all that surprised when she asked it.

I’d cringed that morning, observing how the normally friendly group of women I hang out with at the school gates shifted uncomfortably in their seats, deliberately avoiding Jill’s gaze as she walked alone into the assembly hall.

It was clear no one wanted to sit next to her. Witnessing her subsequent embarrassment when, as we all filed back out, she suggested regrouping at a local cafe only to be met with weak-sounding excuses was even worse.

‘They think you’re lovely,’ I quickly exclaimed, which isn’t a lie. Jill is a sweet and utterly inoffensive woman – there’s nothing not to like.

Unfortunately, though, there’s plenty to pity. And it all manifests itself in the shape of her big, hairy husband Nick. A man who presents himself as the perfect ‘hands-on’ stay-at-home dad, when he’s actually stomach-churningly handsy.

So much so, most of those women are unsure how to behave around her when they’re painfully aware – even if she seems not to be – just how vile a man she’s married to.

Nick is a lecher, with a dubious talent for turning any situation into an excuse to embrace you – your kid coming out of school with a ‘well done’ sticker; overhearing you tell someone you’ve had a bad day, or even a good one.

Pity the woman who lets slip it’s her birthday within that man’s earshot.

The second you see him moving in for a hug – presuming there isn’t time to turn around and flee – you have to brace yourself. Otherwise, the way he crushes himself hard against your breasts isn’t just awkward, it actually hurts.

Realising Nick wasn’t there that morning, having gone down with a bug, came as a relief to any woman who’d had the misfortune to end up seated next to him during one of these school events.

He has a grim trick of putting his hand on your chair just as you’d go to sit down. We all know now to stare first at him, then at the seat and then back to him again until he moves it away.

But a couple of us – another mum and I – previously suffered the mortifying experience of inadvertently setting our bottoms down on his hand before realising his game.

He, of course, laughed it off each time as a silly accident. But I remember feeling sick with embarrassment. Far from finding it funny, I wanted to go home and take a shower. I look back on that, almost a year ago now, and kick myself for not immediately challenging him. His other victim feels the same. But – and I think this will chime with any woman who’s experienced something similar – in that moment, a sickening combination of shock and mortification threw each of us completely off balance.

And, of course, the last place anyone wants to make a scene is at their child’s school – something I’m certain he exploited.

Nick had spent about six months inveigling his way into our all-female group after he got made redundant from his job at a local accountancy firm and became a full-time dad to his and Jill’s kids – two boys, aged six and four. That meant Jill – whose earnings already eclipsed his – could put more into her publishing career, which was taking off, without paying for childcare. 

At first we were impressed, and welcomed him into ‘our’ corner of the playground, where we chat.

Nick was keen to be seen in the same light as the mums – as opposed to the other dads who turned up when work commitments allowed – someone who could help out with childcare in an emergency and join in with the social side of school life.

Back then, he seemed pleasant, charming even – always intently interested in whatever you had to say. He was flattering too, noticing when you got a new haircut and keen to know how you juggled work with raising kids. 

He seemed unusually observant and empathetic, compared to some of the other dads. I wasn’t the only mum to quietly admit I rather enjoyed the attention. But gradually his creepy side came out. He began pretending to brush or pick imaginary hairs off our clothes. Had this happened in isolation, no one would have noticed. But he started doing it to any one of us several times each week.

Or else he’d say a label was sticking out of your top so he could have a fumble while pretending to tuck it in. If you jumped, or showed any sign of alarm, his response was to snigger loudly and say: ‘Easy, tiger.’

We all laughed awkwardly the first time, but soon stopped pretending to find him remotely amusing. Especially when the inappropriate comments started. If one of us turned up looking hurried and flushed, he’d use sexual innuendo to suggest why we might be running late.

We complained about him to each other, but there never seemed to be a right moment to voice any of it directly to him, since we assumed he’d either laugh it off – or pretend to be outraged.

We just stopped showing any interest in him and hoped he’d get the message. He didn’t. Having someone like Nick in our midst was horrible for all of us. But for me there was an added dimension, because I knew his wife better than the other mums.

We’d met a few years earlier through mutual friends and been for drinks several times. But our friendship was now being compromised by her husband’s gross behaviour.

Not telling Jill what he was like at school felt like a betrayal, but I couldn’t face it, for two reasons: first, because I didn’t know how she’d take hearing how disgusting his behaviour was. But also, because I was conscious that for a brief time, I’d enjoyed the attention he’d given me.

Besides, whenever she spoke about him, it was always in glowing terms, saying what a marvellous dad and husband he was.

Bursting that bubble felt impossible. And risky, too. If she challenged him – or me – it would always be my word against his. Anyone outing another woman’s husband as a creep needs far steelier nerves than I possess.

Clearly not buying my ‘they think you’re great’ line, Jill now came up with another theory for being given the cold shoulder.

‘Is it because they think I don’t care about my kids?’ she asked, her voice shaking. ‘Do they think I leave most of the school stuff to Nick?’ I tried to reassure her that this theory was wide of the mark. If anything, I told her, the other mums, frazzled trying to juggle school drop-off alongside work, admired her for that.

At that moment, I almost told her the truth, but I just couldn’t find the words. Instead, I changed the subject and vowed to confront Nick so Jill could feel welcome in our group again.

I didn’t have to wait long. A few days later, Nick heard me coughing and recommended I rub some Vicks on my chest. Predictably, he quickly followed that with an offer to do it for me.

I told him to get lost, using far fruitier language. Another mum quickly jumped in, and told him: ‘We’re all sick of this, Nick.’ When he demanded to know what ‘this’ meant, she crossed her arms and stared coldly back at him. As did everyone else.

He got the message and walked away. The next time he came over, we turned our collective backs. I know that sounds mean and childish. But he deserved it. And it worked. He’s since moved on to another group of mums. I hope he treats them better, or they at least stand up to him more quickly than we did.

• Amanda Blake is a pseudonym. Names and identifying details have been changed.