6 Months As My Brother-in-law's Mistress

Chapter One  

Addie’s POV

“Your husband is cheating on you with my wife.”

The words landed on the tablecloth between our water glasses, flat and unbothered.

I sat back against the leather booth, letting out a dry, cracked laugh that sounded ridiculous even to my own ears.

“Is this a joke, Sebastian?”

I searched his face for a twitch at the corner of his mouth. A smirk, an eye roll, some subtle hint that he was just messing with me.

Nothing.

He sat there in his charcoal suit, broad shoulders square against the booth, swirling a lowball glass of neat bourbon. Sebastian Greene didn’t tell jokes. He was the kind of man whose name made boardrooms go silent before he even stepped out of the elevator. Right now, he was watching me with a kind of certainty that made my throat dry up.

“My wife is your sister, Addie,” Sebastian said smoothly. “I don’t make jokes about family betrayal.”

“Then you’ve completely lost your mind,” I snapped, sitting up and planting both palms flat on the table. “Preston loves me. And Darcia? She’s my sister. We share parents. There is no world where Darcia sleeps with my husband.”

I leaned across the candle, lowering my voice so the waiters two tables down wouldn’t hear me losing my composure.

“You’re paranoid because your own house is a silent hell. Everyone knows you practically live at your firm, Sebastian. Just because you and Darcia haven’t looked at each other in a year doesn’t mean my marriage is rotten too.”

Sebastian didn’t argue. He didn’t raise his voice or flinch at the jab.

He took a slow sip of his bourbon, set the crystal glass down with a clink, and tilted his head. For a second, his gaze flicked down to where my fingers were pressed white-knuckled against the wood, then slowly traveled up to my face. His brow pinched—just a tiny, irritated crease between his eyebrows, like he hadn’t expected me to push back with actual claws.

“Finished?” he asked.

“Yes. And I’m leaving.”

“You can’t honestly tell me you haven’t seen it,” he said, ignoring my half-hearted move toward my purse. He leaned his forearms against the table, closing the distance between us. “For me, it was obvious. Darcia hasn’t been home for dinner in months. She skips the charity galas because she suddenly has ‘migraines,’ but manages weekend trips to spa resorts three towns over.”

A faint, mocking curl touched his lips.

“I pay her a six-figure monthly allowance just to look pretty, because the idea of working a desk made her anxious. Black cards, cars she doesn’t drive, diamond bracelets sitting in velvet boxes on her vanity. And none of it kept her in the house.”

He paused, his eyes narrowing slightly on mine, testing me. “If you asked me, I’d say Preston has been leaving the exact same trail. You just decided not to look.”

A tight knot formed in my ribs.

My mind instantly dragged me back through the last few months. Preston turning his back to me in bed, claiming his back ached. Preston pulling his tie loose at midnight, snapping at me whenever I asked why his firm needed him on a Sunday.

And then… the nursery. The empty room down the hall he refused to paint.

“I’m not ready for children, Addie. Stop bringing it up.”

I swallowed the bitter taste rising in my mouth, forced my shoulders back, and held Sebastian’s stare. I refused to let him watch me unravel over an appetizer plate.

“A man coming home late isn’t a crime, Sebastian,” I countered, keeping my voice level. “Maybe you’re used to buying loyalty with black cards and expensive bracelets, but Preston isn’t you. You want to believe they’re sneaking around because it’s easier than admitting your wife just got bored of a husband who acts like a CEO in his own bedroom.”

Sebastian went completely still.

The bored detachment in his face cracked. A flicker of real heat flashed across his eyes, his pupils darkening as he stared at me across the small flame. He looked caught off guard, like nobody had spoken to him without a filter in forever.

“Is that what you think?” he murmured, his voice dropping an octave, rougher around the edges.

“I think you don’t have proof,” I said, lifting my chin. “You’re just bitter.”

Sebastian held my gaze for three long seconds. He didn’t blink. He looked at me with an intensity that suddenly had nothing to do with business and everything to do with the woman sitting two feet in front of him.

Then he reached into his breast pocket.

He pulled out a folded white paper and slid it across the linen until it hit the edge of my water glass.

“I don’t care that Darcia cheated,” he said, his tone cooling back down to steel, though his eyes never left mine. “Loyalty was never her strong suit anyway. But she looked me in the face three months ago and said a pregnancy would ruin her body.”

My breath caught.

“Darcia is pregnant with Preston’s baby,” he said.

I looked down.

It was an official clinic printout stamped yesterday afternoon. Darcia’s full name. An ultrasound scan attached to the upper corner. Eight weeks gestation.

Eight weeks.

Two months ago, Preston had supposedly spent forty-eight hours at an out-of-state legal conference. That same weekend, Darcia had posted pictures from a mountain retreat where cell service was supposedly dead.

My hands went completely numb. The noise of the restaurant faded into nothingness.

While I was at home folding Preston’s shirts and wondering what I was doing wrong as a wife, he was making a child with my sister.

I stared at the black-and-white scan until the paper blurred. My throat felt thick, but I squeezed my hands into fists in my lap, digging my nails in so deep it stung. I would not cry in front of him. I wouldn’t give him that.

“They think they’re clever,” Sebastian said, his voice cutting through the ringing in my ears. He leaned in closer, his broad shoulders blocking out the rest of the dining room. “They think they can sneak around, run through my money, toss you aside, and play happy family once the scandal blows over.”

He stopped, waiting until I finally forced my eyes up from the paper to look at him.

“I don’t play defense, Addie. I don’t wait for divorce lawyers to negotiate stupid terms. I hit back until the other side regrets ever testing me.”

“And what does that have to do with me?” I managed, proud that my voice didn’t shake.

“I’m offering you an arrangement,” Sebastian said. His gaze swept over my face, lingering on my mouth for a brief second before locking back onto my eyes. “Name your price. Whatever you need to feel protected.”

He tilted his glass toward me steadily.

“Be my mistress for six months, Addie.”