My Secret Crush on My Best Friend's Spouse

I've been married for five years now, and everything seemed perfect. But lately, I've found myself drawn to my best friend Alex's husband, Jack. He's in his early thirties, and there's just something about him that makes me feel... things. It started with small moments, a shared look or touch during a dinner party, that sent shivers down my spine. Recently, it escalated when we were alone at one of those fancy cocktail evenings, and he leaned in close to whisper a joke only I could hear. His breath on my neck left me feeling light-headed, and I couldn't help but wish we weren't just friends. I know this isn't about my marriage or my attraction breaking rules; it's deeper than that. It's about the thrill of the forbidden and the rush of wanting more than what's possible. How do you navigate these feelings without ruining everything? Have any of you been in a similar situation, or found a way to deal with such intense but inappropriate desires?