My Secret Kink and My Fiancé

So yeah... I'm this guy who works the night shift at a warehouse... Not glamorous or anything. But hey, it pays the bills and gives me time to think. Anyway, so there's this thing... This weird kink I've got that nobody knows about except for my fiancé, but even he doesn't really get it. It's just something I do when I'm alone, you know? Kind of like a fantasy that plays out in real life sometimes, only with the consent and safety stuff taken care of, obviously. So there's this one night... I had a bad day at work, and my fiancé was all sweet and nice over video chat before he went to bed. But I couldn't sleep, so I ended up doing something that... well, it kind of freaked him out when I told him about it the next day. It's not like anything illegal or hurting anyone, but it's just so far from what we normally do. I mean, he's a good guy and all... Really supportive of me being who I am... But I guess this was too much for him. He's been acting weird ever since... And now there's this whole tension between us because he doesn't know how to react. I don't really want to give it up though, even if it makes things awkward. I guess the real question is... Am I being an asshole here? By keeping something like that from him before we got engaged and only telling him after? And now, should I just let go of this kink or try to work through it somehow? It feels so much a part of me... So yeah... That's where I am. Thoughts anyone? Sometimes I feel like there’s no way out but forward...