Confession of a Married Software Engineer's Secret Longing

I'm a married software engineer in my late twenties. My marriage has been stable and loving for the past three years, but there's this secret longing that I've harbored deep inside me, one I never share with anyone, not even my wife. It's about exploring something more taboo, something I know she'd never be comfortable with. The fantasy revolves around a dark-haired woman named Lily, who works at our local cafe and is several years younger than me. Lily has this magnetic allure that makes it hard to resist her charm every time I visit the cafe for my morning coffee. Our conversations are light-hearted, but there's an unspoken tension between us, a knowing glance, a touch of hands brushing past each other, that whispers more forbidden desires. One day, after months of these subtle interactions, Lily invited me into the back room under the pretense of discussing some work stuff. The moment we were alone, she pulled out her phone and showed me a picture: it was us, in bed together with her wearing nothing but handcuffs around her wrists, positioned behind my desk at work. I stared, stunned, as she explained that this fantasy had been burning inside her for months too. That night, after dropping Lily off back at the cafe from our secret rendezvous spot where we spent hours engaging in a steamy CNC roleplay involving those handcuffs and more explicit fantasies, I felt utterly conflicted. My wife has no idea about any of this, would she ever understand or accept my need for these darker fantasies? Is it even okay to explore such intense desires when they're with someone who isn't your partner? I feel so torn between two worlds: the safe and loving world I've built with my wife, and this tantalizing but dangerous fantasy life with Lily. How do others navigate these kinds of situations without damaging their relationships? Am I being an asshole by indulging in these fantasies or should I talk to my wife about it all? I need advice.