So i recently started a job with my best friend in the entire universe and its going well so far. We both work night shift but not on the same days. I had two day shift training sessions and then two night shift training sessions and they put me by myself. Keep in mind that the person that trained me read a book the entire time and told me well basically you just stock stuff and then sweep and mop the floor. Ive been holding my own doing what i need to for the morning shift to come in even taking my own garbage out and making extra coffee for the shift ahead of me. Well today i get word that the asst manager doesnt think im doing anything on night shift and so theyve moved me to days!! Fine by me thats what i wanted but what the hell and to beat all she tells my best friend instead of directly coming to me with her complaint. I mean jesus if theres something im not doing then tell me how to do it and i will!!! Meanwhile she makes up her own schedule leaves 5 hours early never answers her phone for important questions doesnt even run a cash register or help clean the store and IM not doing my job...should i say something to her or just let it go? I dont want her thinking im a lazy employee if something i wasnt told to do isnt getting done but at the same time i really dont feel like justifying myself to that fat lazy bi*ch...

I'd talk to her - but calmly and professionally. Good luck

You need to speak to your manager to say that you HEARD from someone other than management negative issues about your performance, that you can't imagine how that happened and if so, how, that you would assume professionalism from management that you would hear such things directly.
In the interim, if you didn't hear it from management, don't believe what you hear.