Would you ever tell your daughter/son that they are stupid?

Absolutely not! I have a 5 yr old & when he makes bad choices, I sometimes tell him, "That was a very stupid thing to do, I don't want to see you do that again." While I may tell him his actions/behaviors were stupid, I would never ever call HIM stupid. NOT ok. I'm sorry you are dealing with that, do not believe them when they say cruel things like that & if it becomes intolerable, maybe it's time to move out?