I usually just laugh at people like that. It enrages them even more. Something like "LMAO, yep going take a looooonnnng nap. Have fun without me!!" It makes them so mad, you're leaving and they can't control that. You just can't let that stuff get to you and must show them it doesn't get to you. Then remember who they are and don't ever associate with them again....that's my 2c anyway.