I am of the opinion that you can’t love everyone. I am also of the opinion that you can not take responsibility for how other choose to react to things.
BUT I am of the opinion that if you do not like a person there is no reason to do and say things (bully) that has the intent hurt him/her.
And it is not strange that so few parents actually know what their children do at school. Because no child would admit to their patents that they are not especially nice. It is not strange, but sad.