Parent threatening teacher

A parent messaged me today claiming that I told her child that God was not real and she was going to post me to social media so everyone knows who I am. This is a total lie— I NEVER speak about God or religion! I teach elementary school. Wouldn’t this be defamation of if she did this?

Is there anything that can be done about this? My admin spoke with this parent and we are meeting on Tuesday and I’m bringing my lesson plans/any work the child did in class. I’m so shocked. The child loves me and I love the student! I cannot see her going home to lie about me. What is going on?? Any thoughts? I HATE confrontation. This is also the parent who I fully believe was a factor in my miscarriage a month ago due to her screaming at me because my team teacher made her child owe recess.

Thoughts?