How to Protect against Sister -Will, Deed, Inheritance, etc?

My sister is one of those highly educated slick as oil people. She is a wealthy college consultant (age 50) who still lives at home....She has OCPD, hordes money, is obsessed with failure/perfectionism. She's so obsessed she even tried to kill me once to get me out of the picture! She has convinced my dad she is broke (but she is very wealthy) ..in turn he made some sort of will for her (he's 83). My Moms name is on the Deed too. Her and I get along great, me and dad do not talk. Mom always avoids the inheritance topic with me,,,,,any way I can prepare to not get totally screwed??? Thanks