My Wife Doesn't Understand My Kink

I've been married to my wife for 25 years now. We're both in our fifties and we still love each other very much, but lately, I've had this thing on the side that's bothering me more than it should. I started thinking about it back when I was younger, around 30 or so. It wasn't something I talked to my wife about until a few years ago. At first, she seemed interested in exploring new things together, but then... well, you can imagine her reaction. She thinks this is just some phase that will pass. She says we're both old enough now and should focus on more realistic fantasies for our age. But it's not a fantasy to me anymore. It's something I've thought about deeply and have come to understand as part of who I am. I didn't know what to do with these thoughts for so long, but then I stumbled upon some CNC roleplay stories online. It's like they opened up this secret world inside my head that I'd never allowed myself to explore before. I don't act on it in real life, everything is consensual and safe when I do the roleplay stuff with others online. But now, it's becoming a bigger part of how I see the world around me too. Sometimes, when I'm out running errands or just driving home from work, I'll pass a convenience store and all these magazines will be sitting there on display, adult-themed ones, obviously, and suddenly, everything feels different. I start imagining them laid out in some other kind of setting instead, like in the back seat of my car or in an abandoned office building. It's weird to admit that this happens to me now. I know it sounds crazy for someone at my age with a long-term partner to suddenly have these kinds of thoughts and desires. But here we are. And I don't really know how to talk about it anymore without upsetting her or making myself sound like some kind of pervert, which I'm not. Just a normal guy who likes unusual things in his headspace. So this is why I've been coming here more often, trying to figure out if anyone else has felt the same way at any point and how they managed it. It's hard living with these thoughts and keeping them completely hidden all the time.