But Robert was surprisingly strong for someone who looked as though he could well have pipe cleaners in the place of bones. He wrestled his arm free, leaning right into Massimo, his milky blue eyes darting about, his tongue making little movements around his lips as though he was anticipating the arrival of a precious moment of clarity.

In a triumphant tone he shouted, ‘You. I did see you. I saw you in the bedroom. With that woman… Cat— Cat—’ He waved at the photograph. ‘The bedroom where there’s purple round the window. Purple, purple…’ His hands were moving, as though he was trying to hook a word out of the ether. Then he forgot about it and said, ‘You were having sex. Sex! Sex!’

Before I could order my thoughts, Massimo’s voice started to rise, ‘Shut up! You’ve just come here to make trouble. Of course I wasn’t having sex with my brother’s wife, you demented old fool.’

Nico stepped towards them and stretched out a hand. ‘Massimo! Calm down! He’s confused, he doesn’t know what he’s saying.’

But there was something about the way Massimo recoiled from Nico as though he was expecting a blow that made me do a double take. Caitlin had been having sex with someone; that much I knew. But with ‘P’. Not Massimo. Surely she wouldn’t sleep with Nico’s brother?

While my mind was gathering evidence, sifting through what I knew for certain and scraping about for other moments and memories I’d overlooked, Massimo and Robert were squaring up to each other, oblivious to everyone else. Robert stood unsteadily with his hands on his hips repeating, ‘I saw you. You! I saw you! Sex with that woman!’

Massimo towered over him. ‘Shut up!’

But Robert wasn’t budging from his four-word refrain of ‘You, I saw you,’ nodding until he looked like he’d dislodge his remaining brain connections if someone didn’t believe him soon.

Nico grabbed Massimo’s upper arm. ‘Mass! That’s enough! He can’t help it, he’s ill.’

But Massimo shook Nico off and shoved Robert, ‘Shut up, you stupid old man!’

Robert went stumbling backwards, crashing into a glass coffee table and buckling at the knees.

Lara flew to her dad, screaming to Massimo, ‘Get off, get off him. He’s only telling the truth, you bullying bastard.’ She booted Massimo in the shins with such force that my own leg jolted. ‘Get away from us!’

Sandro started to cry. Before I could reach him, Francesca put her arm round him, but stood rooted to the spot, her eyes wide open in horror.

While Robert lay groaning on the floor, Massimo grabbed Lara under the jaw with an easy, practised movement, bringing her face up to his. She struggled and his hand tightened. He stared down at her, pressing a knuckle into the soft tissue between her collarbone and shoulder. She stopped trying to get away from him. ‘Don’t you dare kick me, you little cow.’

From the corner of the room, I heard a broken wail of ‘Mum!’ and saw Francesca hang onto Sandro to stop him running to Lara.

And slowly, like the creaking of a steam engine sitting for years in the sidings, all the pistons in my brain started to fire up. It was the way Lara’s body sagged in resignation that told me what I’d missed. She wasn’t fighting, wasn’t yelling or going nuts from the surge of adrenaline that goes with a new experience. There was no shock on Lara’s face, no astonished horror, just acceptance, a ‘Here we go again’.

This wasn’t an out-of-character one-off.

But before I could react, Nico grabbed Massimo by the shoulders and flung him off her. ‘Massimo! What the hell do you think you’re doing? You were half-strangling her!’

Lara rubbed her neck. She bent over Robert, easing him into a sitting position while I became everything I hated in a person, standing with my feet rooted to the sisal carpet, useless as a lamp post, not knowing who to help first. Lara looked as though someone had popped a champagne cork on her emotions.

She was shaking her head at Nico. ‘You’ve no idea what your brother’s like, have you? To you, he’s just a man who gets a bit competitive about sport now and again. But he’s not. He’s a bloody great bully who gets his own way by putting other people down, frightening them and – as you can see – hurting them. Ever wondered why Sandro is terrified to say boo to a goose? Well, that’s why.’

Massimo was saying, ‘Come on, I had to stop you attacking me – you nearly broke my shin.’ He was pulling a ‘Are you really going to listen to this crazy woman?’ face, which I was ashamed to say, I’d seen many times before and joined in with the joke. Now I realised that air of tenseness around Lara, as though she was in a car running out of petrol and it was touch and go whether she could limp to the garage, wasn’t because she was uptight and over-protective, or – as I’d often thought – she needed to ‘loosen up a bit’.

It was because she was scared.

I ran over to her and between us we helped Robert to his feet, shaking and confused, his rheumy old eyes fearful as I tucked my hands under his armpits. I touched Lara’s arm. ‘I’m sorry. I should have seen what was going on.’

‘No one could. Not even me, half the time.’

I helped her walk Robert halfway down the hall to the kitchen, with him resisting all the way, as though he couldn’t trust anyone any more. As Nico and Massimo’s voices got louder and louder in the lounge, she turned to me and said, ‘You go back in and see if you can calm them down. The kids shouldn’t be in there hearing all that. I can manage Dad.’

As I dashed back into the lounge, trying to process the family Armageddon I was witnessing, Dawn’s words came back to me: ‘The way he behaved over Ben was the final straw.’ The words I’d dismissed as the legacy of a bitter ex-wife.

Nico was bellowing at Massimo. ‘What sort of pathetic excuse for a bloke hits a confused old man spouting nonsense, then turns on his wife? What’s got into you, Mass?’ Then I saw a hesitation on Nico’s face, a jag of pain, as though the distant possibility that Robert’s words might be true had just began to sink in.

I looked from Nico to Francesca and Sandro, desperate to stop what I knew was coming next. But before I could bundle the children out of the room, Massimo lifted up his head, making use of the extra couple of inches he had on Nico. A slow smile spread over his face and my stomach churned. He looked like a cat batting a moth, deciding whether to go for the kill or play a bit longer.

‘Let’s just say there are some women who don’t find me pathetic.’ He shrugged his shoulders in a ‘What could I do?’ gesture. ‘Caitlin included. While you were pratting about with your alliums and agapanthus, your wife was a bit neglected. So, let’s say, when you weren’t there for her, I filled the gap. So to speak.’

I was pretty sure Nico had never punched anyone in temper in his life but his whole body was rigid with fury. I was ready to cheer if Massimo got the uppercut he deserved. And if Nico didn’t lamp him one, I might just step in myself.

In a voice shaking with anger, Nico said, ‘You couldn’t resist it, could you? The idea I might be happy, that someone might love me more than they loved you. You had to have her, didn’t you?’

I winced. I liked to pretend to myself that Nico hadn’t ever loved Caitlin. Practical, straight-talking me wanted to believe their love had been a blurry photocopy of our high-definition relationship. I was obviously falling into that second wife syndrome of denying anything good took place before my rescuing arrival.

Massimo laughed, a sarcastic sound that made me want to slap him so hard his ears would ring into the middle of next week. ‘She came after me, mate. Little bit of opera, little bit of afternoon tea, easy pickings. My own wife was just getting her tits out for the baby by then, so worked well for both of us.’

I wanted to throw up out of pure rage. I heard Francesca sob. I spun round. ‘Francesca, come on, love. You don’t want to hear this.’

I caught hold of her arm, bracing myself for resistance but she let herself be led out. I put my other arm around Sandro and rushed them next door to Mum, pushing them over the threshold and shouting, ‘I’ll explain later, back in a mo,’ over my shoulder.

Sandro flew into Mum’s arms. Poor little mite. I’d have to deal with my guilt at the occasions when I’d been rolling my eyes thinking he was a bit of a wet blanket at a later date.

I dashed back to Lara’s and scooted into the lounge to see Nico take a swing at Massimo. There was something of the spaghetti arms about his punch, as though he hadn’t used his limbs for that particular movement before. But he still made contact with Massimo’s chin. Massimo staggered backwards, taking with him a tray of crystal glasses before gathering himself and charging at Nico.

Massimo was the heavier and more powerful of the two but Nico was more nimble on his feet. As I watched them take swipes at each other, a little Lladro ornament was decapitated, a Wedgwood bowl went flinging off the sideboard. I tried to get between them but it was like trying to separate a couple of snarling dogs.