Why do i find this situation uncomfortable?

Please be respectful and use proper pronouns for her. She's a woman and has been one her entire life, even when you didn't know it.

Trans women often try hiding their true identity by taking very masculine jobs, but as you've seen, it never works. Eventually they have to transition.

You can cure your discomfort by learning about her situation. Here's a good starting point for you:

http://t-vox.org/information/transgender-transsexu...

http://ai.eecs.umich.edu/people/conway/TS/TS.html

Why is it shocking?

This person is now happy in the body he was always meant to have, but nature messed up and he was born with the wrong one.

It doesn't affect you at all, so why are you so concerned? Just treat him the same as always, but bear in mind that he now looks the way he has always felt.

You'll get sed to it. Humans are very adaptable.

You'll get used to it.