What should I do, this is all very confusing?

The woman I sit next to at work is pleasant enough but she has recently been ping threatening notes to me. The latest note read: "Why must you continue to exist you pathetic specimen". This is all very confusing as she is really nice to me when we chat. Her threats have gone beyond words and she has recently drawn a picture of a man jumping off a cliff with an arrow and my name over it. She makes a point of farting as she walks past me and has on at least four occasions purposely vomited on my desk. She spits in my Coffee and tells everyone that I'm in to weird with midgets, foliage and wildlife. What I really need to know is how should I best propose to her?