my roommate is disgusting

my (19f) roommate (20f) is so disgusting. she has never once cleaned the washroom in a full year of living together. I think she is eating my food out of the fridge.

The final straw for me was when yesterday, I actually walked in on her eating the Pad Thai I ordered. She was on the couch eating it while I showered ( she doesn't know where the shower is because she has never used it)

I don't know what to do.