Friend Threatened Me If I Don’t Refund Her

Last year, two of my friends and I decided to book a cruise for this year.

We set up a payment plan and each month they sent me their portion through Zelle since only one card on file can pay for the entire cabin.

Fast forward to embarkation day, one of my friends cancels. She says she can’t make it because of some court date.

It’s been a few weeks since the cruise and now said friend that cancelled is asking for her money back.

I told her no respectfully in text and when she called I didn’t pick up, she decided to leave me a nasty voicemail.

She comes up with this whole charade that I overcharged her for the trip and she wants a refund for the whole thing or else she’s going to file a police report, put me on blast on her social medias, and tell my workplace.

What can I do?