Some people are just cruel.Their cruelness may not change but how you handle the situation may change their antics and behaviour. They are getting some kind of pay off from it,perhaps it makes them feel better about their existence.The truth is no one ever feels truly good when behaving this way.Emotinally healthy people feel good and whole when they generously give of themselves.So you must handle this yourself if you are getting nowhere with management and choose to not be run off.Do they know you understand what they are saying or have you played dumb? If so, it's time they know you know the score here! You need to be clever about this so you don't look like the troublemaker.You must also let them see they can't get under your skin and this is NOT bothering you.Even if it really is you need to fake it.The goal is to get them to stop.I wish I. could have examples so I can give you a few things to say, but I understand. Even a simple, You just said I was a horrible nurse and mean to my patients and I find that so sad that you need to put others down...or you just said XY and Z and I want to let you know that sure says a lot about the kind of person YOU are....or that sure says a whole lot more about YOU than me...You must never let them see you upset, emotional or crying....you can even start humming and smiling.Once they see it's not bothering you at all, they may get worse so be prepared.If you can hold it together...they are just testing you...they will often stop the bad behavior!