Confront her

I was horny as hell and she was in fact looking beautiful, but I couldn't get over the image of Kate and my brother together. Yes...I admit...it was something of a turn on. But she was still my wife and he was my brother....

"I accidentally found your video collection," I said.

"What's that?" she asked, clearly confused by the sudden change in direction.

"Your videos with my brother," I said. "I got on the computer while you were gone and you'd left them open."

She stared at me for a moment, wide eyed and her face turning red. I could tell she was quickly trying to judge my mood. She looked both scared to death and exciting by this turn of events.

"Oh...those," she mumbled. "None of that was planned, and it meant nothing to me."

I stared at her trying to untangle my own thoughts on the matter.