Hi op, I've just been through a year of this. It was with my manager who is an extremely friendly, tactile, outgoing person and we have amazing intellectual/professional chemistry. My brain obviously interpreted this as romantic interest and that triggered the feelings to start.
We work in a very high pressure environment and I'm also dealing with a lot outside work (parent's illness, teenagers, probably undiagnosed adhd and autism, peri menopause, all the usual triggers), so it was a fun escape (not always, but once I had it worked out, it was and I used it as such.)
I can give you my advice:
Enjoy it and use it to fuel you. Make it work for you. I directed the energy towards exercise and I now feel and look so much better than when I started. I started dressing better and taking care of my appearance.
I also used it to inject excitement and fun into work, to release the pressure. I didn’t seek out contact and was never ever flirty or inappropriate (this is really important), but I allowed myself to enjoy it when it happened and as he is my manager it happens a lot!
I also directed the energy I was feeling into my relationship and it's now in the best place it's ever been. I used the opportunity to really take a cold, hard look at my relationship as a lot of advice was that this was a sign something was missing. This man could never compare to my husband, so that helps! But my husband and I had been having our own issues, so we had to have hard conversations, and get back on track, which we now have done.
Don't beat yourself up or punish yourself for your feelings.
Decide now that you will never ever act on it or confess anything. Be clear in your own mind that that is not the outcome you seek. Resolve to keep it entirely in your own mind. You are entitled to private thoughts, fantasies, and daydreams. They hurt no-one as long as they remain unspoken.
I was able to think it through deeply and analyse it, as thats how my brain untangles problems, and realised I had literally no desire to make this a real life thing with consequences. I see it more like a little hobby. And now mine has safely faded away and has become a nice work friendship and that's all.