Caught in My Own Web of Consent and Guilt

I'm an engaged grad student who has always been pretty conservative about my sexual preferences. But there was this one incident during a particularly stressful semester where I started exploring more adventurous, boundary-pushing fantasies with my fiancé, Alex. We agreed to push our limits, but only as far as we were both comfortable at any given moment. One night after some wine and late-night conversation, Alex suggested we explore a power dynamic roleplay scenario, he would be in control, I'd be submissive. It was supposed to be consensual and within the bounds of our agreement, but things got complicated when it felt like Alex might have pushed me beyond what I initially wanted. I agreed because I trusted him implicitly and thought we could navigate any grey areas together. However, during one of these sessions, there were moments where I hesitated, saying 'No,' or expressing discomfort, and even asking for a time-out. Yet, in the heat of it, Alex continued, insisting he was only going as far as I consented to. Physically, my body responded differently than my mind did, while my brain said stop, my body moved with desire, seeking friction against his hand guiding me back into position. The sensation made me feel confused and out of control. We eventually stopped when Alex saw the uncertainty in my eyes again, but I was left grappling with intense emotions afterward. Now it's been weeks since that night, and while we've resumed our usual intimate activities without any further exploration of that particular boundary, the guilt and confusion linger. I don't regret consenting to those sessions initially, but I'm struggling with where my own limits lie and how they can change in different contexts. It's a confusing place to be when you're supposed to feel safe exploring your desires with someone you love.