Okay so my FI's sister has really gone off the deep end.She apparently does cocaine and drinks herself to sleep every night. She calls everyone at crazy hours of the night she is constantly causing problems screaming yelling crying.We can't even have our friends around her because she does her crazy things like throwing fits or telling everyone how crappy her life is and starts crying.Don't get me wrong - I do care for her. But we have all tried to get her into rehab, we even took her to California away from here to get help and she refused.She refuses to do anything about her life and just interferes with everyone elses.ANYWAY, let's get to the point. How am I supposed to deal with this at my wedding? My FI is extremely worried as well. I mean she goes from all smiles to screaming rampages within seconds! Totally unpredictable and just insane. Also, she wants to bring her abusive cracked out boyfriend drug dealer as her date...um no?How do we handle this?