I think I'm falling for my married coworker
Why do you think that?
She's a sexy woman. I think she has the same feelings for me too
There is nothing wrong with finding someone attractive for their features. As long as you don't pursue this married coworker then you haven't done anything wrong.
I want to ask her out.
I'd advise against this. Get into a regular romantic relationship with a co-worker is tricky enough without adding in the infidelity on top of it.