The Morning After a Shift at Work

I recently got divorced after four years of marriage. It was mutual and messy, mostly because we couldn't agree on whether we wanted kids or not, but now I'm back to focusing on my barista job while I figure things out. Last night, there was this new customer who came in. He had a bit of stubble on his face, wore a casual shirt that looked expensive, and seemed to have an air of confidence around him. I saw him checking me out as I made drinks for other customers, and he ordered two cups of coffee with extra cream, like he was trying to make conversation. When it was his turn at the counter, I asked how he liked his coffee, and we started talking about where in town he lived. He had an accent that wasn't local but hinted at somewhere cool and far away. We laughed a bit when we realized we were both from out of state. His name is Mark, and after ten minutes of chatting, it felt like I knew him for years. I know it was crazy to do this while on the job, and there are rules about employee behavior with customers, especially that no one should ever go behind the counter unless they work here, but we ended up in the back storage room. It was unplanned; just a moment where we both leaned in as if nothing else mattered. We didn't do anything illegal or overly explicit, but there were touches and whispers in this small, dark space while people could still hear us through the wall from the front counter. I kept thinking about how out of line this was, yet it felt like an escape into something real and raw, for a moment. This is what we did last night: talked over coffee then moved to secrecy behind closed doors in the back room at work. It felt freeing but also wrong on so many levels. Am I the asshole here? Should I have just walked away? How do you balance desire with professionalism? I need some advice, maybe this is normal, and maybe it's not. But either way, what are your thoughts on my actions and decisions?