Hi Audrey Urban
I'm glad you found us! Dealing with a BPD sister isn't easy, especially when you don't know what you are dealing with.
What kind of behaviors does your sister exhibit that makes you think she has BPD? Since when has she been behaving this way?
You say you were considered the "honored one" but that this changed after you offered her advice. What was this advice about? This behavior of your sister reminds me of the BPD behavior known as 'splitting':
Splitting refers to a primitive defense mechanism characterized by a polarization of good feelings and bad feelings, of love and hate, of attachment and rejection.
Splitting is a powerful unconscious force that manifests to protect against anxiety. Rather than providing real protection, splitting leads to destructive behavior and turmoil, and the often confused reactions by those who try to help.
... .
Individuals suffering from borderline personality disorders live in an immature psychological world, fueled by certain constitutional vulnerabilities, where they attempt to shield themselves from conflict and anxiety by splitting the world into all good and all bad. Although this produces an sense of psychological safety, in fact, it renders relationships fragile and chaotic and drives away the very people who are so badly needed to provide stability in the boirderlines life.
According to Kraft Goin MD (University of Southern California), splitting borderlines need a person who is a constant, continuing, empathic force in their lives; someone who can listen and handle being the target of intense rage and idealization while concurrently defining limits and boundaries with firmness and candor. Borderlines require someone who can provide them with the necessary experience of being understood and accepted, and who will not be overwhelmed by their needs, fears and anxieties.
You can read more about it here:
BPD BEHAVIORS: SplittingTake care