I want to stay friends with this crush, but it feels awkward.

I've been friends with this coworker for 3 years. We get along really well both at work and she's even invited me multiple times to her house for drinks, birthdays, movies, etc. we've called each other best friends and she's confided things in me. This isn't to suggest "she lead me on" or anything silly, prior to now, I've only seen her as a friend to and I really enjoyed our time together.

A couple weeks ago, she told me about her boyfriend and my heart sank in a way I didn't expect. I didn't realise how attached I'd gotten to her. I've not told her how I feel because there's multiple reasons why I shouldn't (she's spoken for, we work together, etc) and I want us to be friends because I think she's a really good friend and I liked spending time with her. In fact hearing about this guy makes her happy is actually really nice.

...it still hurts though.

A bad habit I have is overthinking and anxiety. What was once 2 friends who got on really well is now one person worrying over every awkward silence, every joke that doesn't land and comparing himself to what our conversations use to be like. I'm kinda scared around her now in the sense I think I'm making things weird. Actual experience says otherwise; we still have good times together but I can't get out of my own head and sometimes it's hard to think of things to talk about.

I know it probably can't go back to exactly the way it was before, but is there any advice for navigating this?