My Fling in a Coffee Break - Advice Needed?

I never thought I'd have this kind of thing happen at work. You know that new barista, Alex? Yeah, we started talking and it turned out he was open too. It's been tough keeping the boundary between work and my personal life clear since then. Anyway, one day, during a break when the shop wasn't busy, we got into a deep conversation about our past relationships and how being in an open relationship has changed us. There was just something so intense and intimate about it, despite everything feeling new. Then out of nowhere, I felt this urge come over me that I couldn't ignore. It's like when you're in the middle of a really passionate conversation and suddenly your body just knows what needs to happen next. Alex seemed to feel it too because before either of us could stop ourselves, we were in one of the back rooms. I'll admit, my hands started exploring every inch of him, from his toned abs down to his firm thighs. He was equally eager, pressing me up against a wall and starting to kiss me deeply. The feel of his body against mine sent shivers through me as I slipped my hand into his pants. It didn't take long before we were both in full gear, exploring each other thoroughly. I mean, it wasn't just about the sex either, though that was incredible, but there's this connection between us now, something deeper than lust but not exactly love either. I'm torn because while I enjoy Alex and all that comes with him, part of me is still committed to my main partner back home. So here's where it gets tricky: what do I do about this dynamic? Is it normal to feel so strongly for someone you've just started seeing casually when you're already in a relationship elsewhere? Am I being fair to both sides or am I playing with fire? Anyway, any advice would be appreciated. It feels like every decision now is a balancing act between what makes me happy and what's ethical in the situation.