MY TWIN SISTER

I'm worried sick about my twin sister she's not her normal self and I fear she may have a serious illnes. I can't turn to my family because the issue upsets everyone they'd rather go about things like there isn't a problem when I discuss it with my fiance he thinks i'm over exaggerating. I feel physical pain when i speak to my sister and she claims there are cameras in every crevace facing at her or when she's demanding i split the money that "they" are paying me to pretend to be her sister because she needs the money. The other night my home phone was shut of cell phone battery so low i couldn't make an outgoing call and i didn't get any sleep thinking she might have committed suicide. I'm not allowed to go to her house without telling her and when i do tell her she's always totally against seeing me or anyone else.