I think a crush (that combination of desire, longing, admiration and obsession) is one of those things that steps in to fill a void. At a guess (just a guess?) has there been a recent change in your life OP? e.g. children leaving home, a house move, friend moved away, family member unwell? Alternatively, has something changed in your marriage, or have you noticed something that's happened over time?
My crush was stupid and inexplicable- aimed at an ex girlfriend's sister, (a long time ago!!) The unattainable aspect is almost a compulsory component isn't it? But the 'certain indescribable something' keeps the compulsion wrapped up in a mystery .
You could try a thinking exercise....?
So maybe break it down for yourself. You admire this guy? Try and spell out what it is about him that's admirable. (Eg confident, stylish, competent, smart?)
Then go through what makes him desirable (it could be some of the previous qualities plus - attractive, tall, warm, popular). These will all be very ordinary thoughts that others might see and agree with!
Then - what makes you feel a sense of longing? You can admire without desire, but not when it's a crush! So when do your thoughts turn to him, (in the morning, in any quiet moments, on way to work?)
And finally - what do you honestly want to happen, in fantasy (you can be as imaginative as you like) and then see that it's really fantasy And then realistically - next time you see him - what do you actually hope to happen (a text, a call, lunch together)? And then maybe see that what you actually hope for is so far removed from the fantasy you are feeding.
It's just a thinking exercise, to unravel or demystify your feelings a little. Sometimes the mystery is part of the appeal.
We aren't punished for our thoughts OP - only for what we do. But intrusive thoughts or compulsions can interfere in our lives, and affect relationships.
I think it's quite nice that you have such passionate feelings - your not quite spent up yet are you? Lol! You can use that discovery to create things in your own life and focus your passions for what can really happen - rather than the best you can realistically hope to happen next time in work with your crush.
I've no idea if that is any help OP - just an attempt at something practical you can do about addressing the way you think about the way you feel.