Caught in the Moment of Passion

I've been engaged for five years now. My fiancée is incredible, beautiful, kind-hearted, and so understanding. She knows all about my past too, including an old habit from before we got together. It was always CNC (consensual non-consent) roleplay with a friend, just fantasy stuff that helped me deal with stress. But this time, I strayed. I've been working at the university for decades now and have seen all kinds of students come through my office looking for help, advice, or simply a friendly ear. Last week, there was a young woman named Laura who came in during one of those particularly stressful days when everything seemed to fall apart. She had an issue with her thesis, but what struck me more than the academic trouble was her beauty and grace under pressure. We exchanged emails and I helped guide her through some problems over the next few weeks. One evening, as she thanked me for my guidance on a particularly tough section of her project, I felt something strange happening within me, something that hadn't happened in years since I had found true happiness with my fiancée. It was like old memories came flooding back and before I knew it, Laura and I ended up sharing an intense moment that I can only describe as a CNC fantasy come to life. The reality of what we were doing didn’t matter; our mutual attraction and the thrill of this forbidden situation made everything feel surreal. I've never felt more ashamed of myself than after that encounter. My fiancée would be devastated if she found out, but even worse is knowing I betrayed her in a way so personal and intimate. We are both adults who agreed to play with CNC before, but something about this feels different. It wasn’t just roleplay anymore; it was real. And it's left me questioning everything, my fidelity, my judgment, and if the love we share can ever be strong enough to overcome a moment of weakness like this.