...So I Did This Thing

I've been married for about twenty years now to my lovely wife Karen. She's forty-five too, we're aging together in this crazy rollercoaster of life, you know? But lately, well, I've kinda developed a rather unusual fetish. It's one that isn't exactly shared with her, and it's something that's been bothering me for weeks. So here’s the backstory... About six months ago, I started watching these adult films online, just for fun, you know? And in these movies, they'd sometimes include a character who was into this really specific thing. It involved some roleplay, and well... let's just say it wasn't something that most couples typically explore. I found myself becoming more and more interested in the idea of enacting this fantasy with Karen, but I knew she wouldn’t go for it. She’s conservative, and we have a very vanilla relationship compared to what these films depict. Still, there was something about the way those performers looked at each other, the intensity... Anyway, last week, while Karen was out of town visiting her sister, I got this wild urge. I told myself it wasn’t going to happen, but then... I just couldn't resist anymore. So I found a local dungeon and spent an evening there playing out my fantasy with someone who knew exactly what I wanted... Now here's where things get messy. The night was heated, to say the least. Let’s be clear about this: when I got into position with [her], it was explicit, very much so. We talked through everything beforehand and used lots of lube and toys to make sure we could explore safely... but there were moments where I had to stop myself from blurting out her name instead of the character's. And that’s what has me worried, honestly. Did any of you ever do something this big without your partner? Is it normal for people in long-term relationships to have these kind of urges and go through with them alone... or should I just be seeing a therapist already? ... Tell me, is there anything wrong with indulging every once in a while when your spouse isn't around and you've found someone who gets what you want? ...