Playing with Fire in an Open Relationship

So here's the thing, I'm 25 and nonbinary, and I've been in a loving but open relationship for about two years now. My partner, who we'll call Alex, is also super down for experimenting outside of our monogamous pact. It started off easy enough; first with some casual hookups at parties or meet-ups to keep the spice alive. We even made it into a fun thing where we'd share experiences and stories. But recently, things have gotten more intense. Last week, I met someone online who was down for hardcore roleplay involving dominant/submissive dynamics and power play scenarios. Let's call him Jake. He’s also in his late 20s and pretty open-minded about swinging and other kinks. We talked a lot beforehand to make sure we were both comfortable with the limits and boundaries. The day came, and it was wild, Jake tied me up, blindfolded me, and took control in ways that pushed me way past my usual comfort zone. It was exhilarating but also scary as hell to feel so utterly vulnerable and submissive. We didn't stop there though; I ended up getting into some pain play too, which definitely wasn’t something I thought would turn me on. But it did. The next day, I had this weird mix of wanting more but feeling anxious about where the line is drawn with Alex. Should I tell him everything that happened? It felt like betraying a trust by withholding info, but then again, I didn't want to break his stride either by suggesting something too intense. So here’s my question: am I being overly paranoid or selfish by keeping quiet about this? Is it normal for there to be these kinds of concerns when you're exploring your limits in an open relationship? Or is the only way forward honesty and transparency, no matter how uncomfortable the details might make things between me and Alex? I'm kinda torn on what's best.