quarters

So today my nephew came up to visit me at work. I work at a pool. While he was in the bathroom changing after going swimming. One of my co-workers walked into my office and told me; How horrible a child he is. How my family spoils him. How emotionally disturbed he is. How he's probably going to end up in jail because he's so bad. Then when he comes out she starts saying the same things to him. He's 4! After my family left and the opinionated person left the room, a customer who overheard everything said I should "Fire that bitch!" Unfortunately I can't. I don't hold the position to remove her from employment and the person who does would never fire her. If he wasn't married, he'd probably be trying to date her, if he isn't already dating her? I talked to my family after I got home and it bothered them too, and they didn't hear most of the conversation. What gives someone the right to say such cruel things about a child? I don't even know how to articulate how angry I am about this ordeal. This person has made comments before about him being unruly, but I calmly explain that he is a small child and little boys don't like sitting still, especially when they know all the skills the teacher is teaching because he; A) already taken the class before B) is only in the class because the teacher thinks no child should move up until they take the same level 2-3 times C) he swims 3 days a week to practice the skills D) he loves to swim, not sit. He isn't a dog!
Anyways that's my rant for the day.
If anyone has an idea for how I can handle this girl without violence throw the idea out there.