How do you deal with people like this?

i know someone like this. she was a girl in my 5th grade cl and she was manipulative and even cruel sometimes. she did all the things you decribed. later it turned out that she was being abused at home. now i am not saying that this applies to everyone who acts like this, and i am deff. not trying to say that this behavior is right. but sometimes, that is how people react to get attention that someone isant giving them. or to get poistive attention or feel sympathy. yes, its annoying, but you have to think to yourself "i wonder whats going on in their life that is making them act like this" its hard sometimes, but ultimately its the right thing to do.