A Slip in Control

I've been in an open relationship with Alex for about two years now. We met when I was transitioning and it felt so liberating to be free from the pressure of labels or expectations, just being together as equals. I had come out earlier in my twenties and slowly started feeling more comfortable in my skin, which only strengthened our bond. Our relationship is mostly non-monogamous. Alex understands that while we love each other deeply, the world isn't always kind to polyamorous relationships, so it's important for both of us to have some independence. We've agreed on a few rules: mutual respect, open communication, and no emotional or physical boundaries between our separate partners unless one of us feels uncomfortable. Last month, I met someone at a queer event in town, let's call her Dana. She was kind, witty, and clearly comfortable with herself. Over the course of a week, we spent lots of time together, chatting online and then meeting up for coffee and walks. There was an undeniable chemistry between us. One night, after we'd been seeing each other regularly but officially agreed to take things slow, I invited Dana over when Alex was away on business. We talked for hours in my apartment, mostly catching up and just being ourselves, until late into the evening. As we sat there, a sense of longing washed over me, it felt like that perfect moment where you know you've found someone special but also want to respect boundaries. Without really thinking about it, I crossed the line and ended up kissing Dana, telling her how much I'd wanted this for so long. She was hesitant at first but then melted into my arms, our kisses deepening until we were both breathless and flushed with desire. It felt right in that moment, a surge of passion and intimacy. But then the next day hit me hard, Alex might feel hurt by this slip up, especially because it went beyond what I'd committed to in my polyamorous journey. So far, Dana and I have decided to wait and see where things go without rushing into anything physical again until we talk everything out properly with both of us. I'm worried now about the impact on Alex; it's not just a slip-up but a momentary lapse in judgment that went against our agreement. Am I being unfair to Dana by stopping things cold? And will Alex ever forgive me for this?