Father in Law trying to sue me for having security camera in our house

Looking for what my legal rights are for having security cameras inside our house. We have 2 cameras inside and 1 doorbell camera outside. 1 camera is overlooking our family room and front door 1 camera is overlooking kitchen, back door, and garage door. 1 camera is the door bell

Father in law has apparently consulted with a lawyer about suing myself and my father (who doesn’t live with us. He lives 1400 miles away and has no access to the cameras or our house) for filming and recording him and his wife without their consent. For example, my wife and I let them watch our daughter who is under 4 years old while my wife and I have our very rare date night.

Father in law has threatened to call my place of work to “ruin me” which I’m not sure how to take that or protect myself from that sort of slander.

Any thoughts and advice are more than welcome. I have contacted a local law firm to get some advice as well.

Use Location: Missouri