1st of all it’s sounds like potential blackmail, which is a crime. Remember that part.
She reached out to you, nothing has happened yet but if it does that’s important information.
Secondly if you don’t have a punting phone get one. Or if you have one just change your number.
Reverse search yourself, see what comes up under your current number and if you can remove it, remove it.
Don’t panic. Nothing has happened yet, and you haven’t said you’ve done anything wrong, so nothing to worry about on the grand scheme of things.
If you get consistent messages or calls, log it and use it for a police case of harassment and potential blackmail.