I'm going to tell my brother in law's wife that our in laws think she's fat and stupid.
Why do you think it's okay to tell her that?
No particular reason. I just feel like it.
It is not good to tell a person things that will make them upset with another person. It will damage the relationship of everybody to hurt them and you had no reason.
I want her to feel what it's like to be talked about at every moment. Stupid bitch.
Causing drama in a family is mean. It's also likely to make everyone turn their bad feelings onto you, which is probably not what you want.