A Secret Fantasy Roleplay

I've been dating casually for a few months now, but nothing has felt quite serious yet. A couple of weeks ago, I decided to take things up a notch with this one girl who I really enjoy spending time with. We agreed on roleplaying something a bit more taboo, she said it would be fun and consensual, but my mind keeps going back to it, replaying the scenario over and over again in my head. We pretended I was her college professor and she was my student. She had this fascination with me as an authority figure and how it made her feel submissive and vulnerable. It felt wrong at the time because of course a real relationship like that is unethical and illegal, but our boundaries were clear: no one would get hurt or pressured, just a playful exploration of power dynamics. I remember looking into her eyes during this roleplay and seeing genuine interest there, it was hard not to blur the lines between reality and fantasy. Since then, we've kept things light, but I can't help feeling guilty about it all. It's like there's this dark secret that lives inside of me now.