So last night I told my oldest sister not to contact me anymore

[Egalitarian Thug]

11. Life's too short to suffer stupid people. Some of the great myths of our dominant culture is that

family is the most important thing, that when the chips are down it is they that will help you get through, that the great unspokens (religion, politics, and money) are not worth losing your relatives over.

Well, a lifetime of experience as a serial monogamist has taught me that this is pretty much unadulterated BS. While these myths have proven true much of the time in my own family (except the money one, never get between a WASP and their bank account), I have had the opportunity to learn first-hand that in many (most?) other families none of this applies except when they are looking for help from you.

If your sister is as big a nut as you indicate, cut your losses and make your own family from those that have proven themselves reliable through actions and forget the rest.