Jekyll and Hyde and back again

[Releaseme]

Ever since my father died two years ago (April 1, 2015 btw) my sister has wreaked havoc in our family. Even before my Dad's death, she would play mind-numbing guilt games with everyone: friends, neighbors, family members (including my Dad, who had a stroke and couldn't get up to kick her but.  My sister's children haven't spoken to her in over five years.  Now I'll be the first to admit I am far from perfect.   But I live with my Mom, who will be 90 years old next month, and I do the best I can to take care of her.  My sister, was my Dad's primary caregiver, now considers herself my Mom PCG.  My sister is highly resentful of the fact that I live with my Mom. She has done many underhanded things, and is constantly belittling my Mom to her face. 
A couple of days ago I was leaving for work and I was supposed to drop my Mom off at my sister's house. My Mom said she wasn't feeling well. We'll, of course, my sister took offense to this and told my Mom to have me call my sister.
So I called her back and, of course, typically tried to recruit me into her schemes.  After getting off the phone with my sister, my Mom was crying because she felt guilty for not giving in to my sister. (Keep in mind, my Mom is still grieving my Dad). I felt so bad for her and I told her not to feel guilty, that my sister was "toxic", and that she is trying to control every aspect of my Mom's life. Welĺllllll, I had forgotten to hang up the phone after talking to my sister, and the waste matter hit the spinning blades, shall we say.  I got a phone call from my sister ripping me to shreds.  I tried to email an apology, but, having the upper hand, she pile-drove me into the groundetails.  The ultimate victim in this is my Mom, whose grief has been exponentially complicated by my sister's out-of-control behavior.
Sorry for being so long-winded, but this is just the tip of the iceberg.
I'll wrap up by saying two things that I have found
 In dealing with my sister:

1. She wields the defense mechanism of projection like a highly-skilled craftsman.

2. On one day, in her eyes, I could be the Second Coming of Christmas, and the next day I could be the Anticristo.

Thanks for letting me prattle.

[Kwamina]

Hi Releaseme

I am sorry you lost your dad two years ago. Losing a close relative is often very difficult for people. You mention your mother still grieving his passing, which of course is understandable. How have you been coping yourself? Do you feel like you've been able to grieve your dad's passing?

It's unfortunate what's going on with your sister and how this is also affecting your elderly mother. I can see how your sister overhearing what you said about her could trigger her. Was this the first time she heard you so directly express how you feel about her behavior?

1. She wields the defense mechanism of projection like a highly-skilled craftsman.

2. On one day, in her eyes, I could be the Second Coming of Christmas, and the next day I could be the Anticristo.

Projection and splitting, yeah that definitely are classic and textbook BPD behaviors... .well at least you got to be the Second Coming for a whole day

But on a more serious note, dealing with projection and splitting can be very difficult. How long have you suspected your sister might have BPD?

You mention her children not speaking to her for over 5 years, do you still have contact with her children? How would you describe the way your sister treated her children?

Take care and though your screenname is Releaseme, I'll still add some hugs