Is this a 5yo phase? My 5yo will hit and bite me when she's angry, usually when she's tired or hungry. She doesn't do it to anyone else and she knows it's wrong because afterwards she hides her self away crying 
I try to remain calm but it's difficult sometimes because it really hurts! I've been walking away when she does it but she completely freaks out because she thinks I'm going to leave her (she's quite clingy and sensitive generally, and has to be peeled off me to be taken into school).
Is this just a phase? Is there a better way of handling it?