I Need Help

I need advise tips on how to get Shelby out of the way. I don't like her. She hogs all of the attention, "Cause she is shy and needs to have people around her." Blah, she is funny looking and mean. Just because she is Tiff's cat doesn't mean anything. I was her first not her. I hit her this morning and maybe I knocked her into the wall, and Tiff had to see it, she wasn't to happy that I scared her cat like that, and made me leave her alone. I don't know what to do. Any advise?