My Secret Kink Exposed and Loved by All My Lovers

I've been in an open relationship for about five years now. It's a wonderful arrangement that allows me to explore my desires and connect with people who are into the same things I am without feeling guilty or constrained. One of those desires is cuckolding, something I never thought would be possible until my current partners and I started discussing our kinks and fantasies. So, there we were one evening, a small group of us, talking about our various interests over wine and cheese when I decided to bring it up. 'I've always been intrigued by cuckolding,' I said nervously. My long-term partner, Alex, smiled at me encouragingly while the others seemed intrigued but curious. We talked it through for a bit. The concept of sharing my sexual control with another person was thrilling yet daunting all at once. It's one thing to fantasize about something, quite another to actually do it. But after some thoughtful discussion and planning, we agreed that if I ever wanted to experiment with this kink, it would be okay. The moment came during a large get-together at a mutual friend’s place last month. There were several people around, all of them comfortable with the idea, so why not? Sheena, one of my newer partners who had shown interest in cuckolding from our earlier conversations, approached me that evening and whispered her readiness. We went into a private room, closing the door behind us. The anticipation was overwhelming as she started undressing slowly, revealing herself to me piece by piece. My body responded immediately, heart pounding and skin tingling with excitement. Sheena came over, sliding her hands up my chest, pulling me towards her lips for a deep kiss. Then it happened; the moment I had longed for but feared in equal measure. She undid my belt and zipper, reaching into my pants to guide his erection out of them. Stroking slowly at first, then with increasing urgency until she guided him to swallow her entire length in one fluid motion. He felt so warm inside her mouth, the sensation overwhelming. The climax was intense, both for me as I watched and participated, and for her as she performed this act under my watchful eye. Afterward, we shared a kiss that encapsulated all our emotions from fear to exhilaration. So here's where I need advice: Is it common among open relationship folks to experiment with cuckolding? Or am I the asshole for bringing something like this up in a social setting? Would love your thoughts on whether or not what I did was normal or crossing a line.