How can i deal with my insane grandmother!?!?!?

my grandmother is visiting my family for another week (shes been here a week already) and shes making my life living hell..she thinks anything i do is "wrong" even if its just playing guitar.. the first night she was here she walked around my bedroom saying that everything i owned was bad for me (fish are bad?) shes done this: looked through my stuff, she keeps calling my Kathryn- not my name (im serious my name is Kat), she insults my friends, and thinks im a devil worshiper- i cant explain that one, she also said i was wearing "bad" clothes- jeans and t- shirts are bad?? how can i deal with her for another week!?! i cant tune her out or ignore her since shes in my house..... help...