My nephew (sister-in-laws child) is 6 and he is a real brat towards my whole household. I could handle annoying bratty kids normally because they are kids but he is really unkind to my 3 year old by saying things like “you never play the right way” or “you’re not good at this”  and the worst one was “you’re really annoying and I hate coming here” just really shitty things you shouldn’t say to a 3 year old. and I’ve tried being polite and reasoning with the 6 year old and it’s usually met with “why” “my dad told me I could do this” “you aren’t my boss” etc etc etc. so finally I told my wife that I’d like her to talk to her sister about him and she told me I’m being a bully to a child and my BPD makes me irrational about stuff like this because of my own past traumas. I told her my past with bullying is precisely why I can’t tolerate my 3 year old being picked on. So he came for a sleepover and started off great but then progressively got more mean as the night went on. So finally I told him if he can’t be kind then he will have to go home and he started crying which obviously made my wife mad at me and now it’s a whole thing.  Am I wrong for not wanting my 3 year old around a bratty 6 year old? especially one that is mean to him. Why do we have to like children because of the fact they are children.