A Slip of the Tongue in Private

I met my partner, Alex, during our undergrad years and we've been together ever since. We share a lot of common interests and support each other through our personal struggles, but there's this one thing that's been bothering me lately. Last night, we were just lying in bed talking, and I don't know what came over me, I admitted to something I never would have expected myself to say. It wasn't anything I actually wanted or planned; it was more like a fantasy I had once, but I thought it died with my twenties. I told Alex about this old desire of mine, involving some playful control and dominance. The moment the words left my mouth, I could see in his eyes that he was surprised and maybe even uncomfortable. We haven't discussed it since, and now I'm not sure if bringing it up like that ruined everything or if we'll be able to get past this weird feeling of tension between us. Am I overthinking this? Is there a way to salvage our relationship after sharing something so personal yet unexpected?