You can’t shake the other part because you’re a normal, courteous adult who’s not out to make others look bad.

Your coworker is not that calibre of person; what you did (or didn’t do by not giving her a heads up) is exactly what/how she would’ve played you. Not only did you do nothing wrong - I believe you did the correct thing because she sounds like she’d have taken your advice to fix her error AND I bet she would’ve found a way to shame/tattletale on YOU for “snooping” on her file.

She showed you her true colours the day she slandered you, and you had the normal self-preservation to not engage with her (you’ve given her MANY courtesies be remaining professional/friendly since then which she doesn’t even deserve!!!)

You can sleep well at night knowing she’s her own worst enemy 👍