Caught Myself Straying

I've been engaged for six months now, and things were going well. But last night, I found myself sneaking into an old chatroom where I used to meet strangers for explicit text chats back in my early twenties. We'd never do anything beyond talking, safe but still incredibly exciting at the time. Now I'm a different person with a partner who means everything to me. Yet there I was, typing out an introduction that I hoped would get rejected so I could turn away and think 'never again.' But then someone replied, and before long we were discussing intimate fantasies and desires in excruciating detail. There's something thrilling about the anonymity of it all, the freedom to talk about anything, and my fingers couldn't stop typing. We ended up planning a video call for later that week where I'd wear nothing but lingerie. It was supposed to be just talking, but we both agreed on a secret code word if things got too intense or either of us felt uncomfortable. Still, even as we talked, my body reacted powerfully; my heart raced and I felt a wet heat between my legs building up quickly. When the call ended abruptly when my partner called asking where I was, I had to explain myself. But how can I tell them about this? Am I just curious or is there something deeper here? Have you ever found yourself slipping back into old habits like this and what did you do?