Work crush..help me be normal (light hearted)

[again2020]

I have a crush on a man at work which has developed over the last few weeks. It's from a distance, we have never spoken apart from basic greetings. We don't work for the same team but share the same space (laboratory).I'm in a long term relationship with a DD and I've heard he has a girlfriend. I know the advice would be don't act on it but I'm basically doing the exact opposite...I pretend he doesn't exist and he must think I hate him as I'm standoffish,don't take him on at all as I'm mortified by it! 🙈
I'm friendly with a couple of his colleagues and once or twice they've started conversations with me while he was around and I've shocked myself by being ruder than I intended to be. I'm really embarrassed and still the same 14 year old inside who would 'die' if a guy I fancied knew. I'm just trying to be too cool 😂
I don't know why it bothers me so much, he must be a good 10 years younger than me and I'm a mum pushing 40 so he'd never look at me.

How can I just be normal?!

Well I think you know it's unlikely it's reciprocated and he has a gf, I would build on your confidence to talk to him though just so he knows your friendly and not offish, quite often when you get to know someone the attraction fades, strange but true! Sometimes

Thank you @sageflower I needed to read that. I think you're right. I will try to relax about it!

How does he behave towards you? What is this crush based on? I don’t think him maybe having a gf and being younger than you is an guarantee at all that he wouldn’t fancy you. And possibly quite the opposite.

How does he interact with you?

He seems normal ish, although shy. Occasionally we catch each other's eye but that's it. I go running at work and ran past him once and my stomach did back flips.. I'm an idiot 😂
I just find him very attractive, and that's rare for me.
I won't do anything about it before anyone says anything...as you can tell I wouldn't know where to start!