How to deal with a delusional classmate?

One of my classmate, lets call her x has a psychiatric problem and refuses to get treatment. She and her family believe that there’s nothing wrong with her and continue to feed into her delusions. She continues makes up stories about people being in love with her, trying to assault/ harass her, everyone being jealous of her. In the beginning everyone was supportive of her and tried to get her proper treatment but when she started putting all these blames on us, everyone distanced form her. I really tried till the end but it was impossible.

For eg: she would come up to my room and ask for things like my toothbrush and would say she’ll return it after washing (i mean girl thats gross who tf shares toothbrushes), then she would insist on sleeping in my bed with my blanket even after telling her i’m uncomfortable with that, would randomly stand outside your door to listen incase you’re bitching about her (which we didn’t because no one wanted to get involved in her drama), then complained to the dean how she was being discriminated because she belonged to SC caste when majority people didn’t even know that.

I’ve cutoff contact since then but now she purposely hangs around near me and says random things like “chutiya, ugly, bc” for literally no reason. Haven’t even talked to this girl since 1st year and steer clear of her because she keeps threatening everyone with the dean card. I’m so sick of this bullshit but I’m sure the minute I say something, she’s going to run to the dean with a fake sob story.