GOT INTO AN ARGUEMENT AT WORK!?

okay i've been working at zaxbys for about 2 months now and every since iv'e been working here this girl has been on my case. every time i make a move she has something to say even managers do things like dumping the tea in the front but as soon as she see's me doing it she says something even if the other co-workers do something she doesn't say anything don't let me do it though she have to intervene she's not even a manager and she gets on my case more than they do. as a matter a fact they RARLEY even gets on my case! im cool with everyone else though but since day one she's been talking about me and being on my case saying stuff like "okay but when you get fired" or what not and she and everyone else take cookies when there not suposed to but when i take cookies she says okay you should,t do that cooperate is gonna get you or what not but then she goes right over and dooes it everyday!! ? -___- and while i was taking some today she was like cooprate is gonna see you and im like okay im just taking a few like you and amanda did early and she was like i only took the broken ones (wich was a bold face lie because there were no broken ones) and she was like okay cooperate is going to see you and im like "well oh okay then" then she says im the wrong one to get an attitude with" and i was like im am too. then she says okay you don't wanna argue with me. and im like your right because im to mature to sit here an argue with you. and the she went to the back and was like Robert (one of the managers) get this retarded girl and i follow her then i express to him about whats been going on this whole time (because she tried to snitch about me taking cookies witch she does everyday) i rarely ever get into arguments but i was just tried of the abuse . i don't know how i should handle her he told me to just ignore her but it's hard to what would you do?