My mom treats me like crap

My brother just left for college and everyone said that she would be giving me a ton of attention, but apparently now that her pride and joy is gone, she doesn't know what to do with her life and she's always in a bad mood. She slapped me this morning for moving a bag that I fell over like 5 times. I kept falling on my face in the dark and it hurt. Anyways just now she got upset because she told me to leave her alone because I was sitting in the living room with her and I said fine and tossed the pillow I was holding into her lap and she got up and started yelling because I need to treat her with respect and stop "throwing my shit at her" .. she's been cussing all the time at me the past couple days and I don't know why or what to do.