Caring for dying sister. Advice on inter family communications?

I'm writing to ask for support about inter-family communications. My older sister Bea is dying of multiple myeloma. (I have 3 sisters -- Essy and Cee are my younger sisters) Since her diagnosis in Feb., Bea was very positive; my family has always said about her that she lives in a fantasy world -- so much so that as radiation and chemo progressed, she went into denial about her physical abilities and the state of the disease. Her cancer doctor (Dr. G) didn't help at all, never telling her the truth about the cancer’s progression, the seriousness of it or the results of the latest MRI in mid-July which showed extreme advancing of the myeloma. During this time, either b/c of the cancer or the heavy drugs when she was in the hospital, she had a lot of difficulty remembering what was happening, who her doctors were, their names, what procedures they were doing and why. She eschewed all responsibility and her attitude was “I don’t want to know,” and” just let the doctor decide what to do, it's out of my hands, I don't care." I stood beside her neurosurgeon who told her the details of the mid-July MRI they did under sedation b/c she was in so much pain she couldn’t hold still. She doesn’t remember to this day what he said, except now she is able to remember “my spine is crumbling,” but she doesn’t remember who told her that. During this time, we stepped in to help care for her, since she was not able. Our role was to advocate for her and to keep her safe, and clean and well-cared for.
Her doctor (Dr. G) wanted to begin chemo again in July without being clear with her that it was palliative. During earlier chemo sessions this year she’d had 5-6 ER and hospital admissions due to the treatments, which was very difficult on Cee, the chief caregiver. Bea was in complete denial that the chemo caused her any issues at all. And we 3 sisters had wanted some clarity about it, and finally so did Bea, so I wrote to Dr. G. on Bea’s behalf, asking him that he talk with her frankly about the details of her care, her health, and the current status of the disease.His response was to transfer her to a new doctor – this all happened Monday this past week while I was there; and until the middle of the week, I thought all of us sisters were on the same page, not aware that Bea was beginning to want to face this disease and take over her own care.On Tuesday, my sister Essy visited Bea and said that Bea was ready to face this with the new doctor alone and was ready to ask her own questions. (Cee and her husband had left town for a well deserved rest, and we promised not to bother them.) So when my sister Essy told me to stay out of Bea’s business and let her handle this, I was taken aback. Essy became angry at me for questioning whether Bea was ready to dictate her own care. I wasn’t clear that: • Bea was even talking about being ready to talk frankly about her condition and its effect on her body with the new doctor and • That we 3 sisters were shifting out of the caregiver role we’d been given, since Bea had eschewed all responsibility for it. Apparently now Essy said, she was ready to step up – but Essy did not discuss this with me.It wasn’t clear to me that Bea’s attitude towards accepting her own care had changed, or that we sisters were backing away from the responsibility we’d assumed during her absence of caring for herself.My sister Essy said Bea’d written out questions for the new dr., and I was concerned that Bea was just trying to divert and control the situation as she had in the past and possibly not ask the questions. Essy became furious with me and began attacking me personally, she was disrespectful to me, she threatened, bullied, and said cruel things to me. I asked her to stop talking this way to me, and then she went in her room, slammed the door and locked it. When I knocked and asked her to please talk with me about this new role for us as caregivers, she said, “I’m recording you and I will keep this and present it against you.” She later wrote me in an email that I was “harassing” Bea. Since both Essy and I had stayed over an extra day to go to the new dr. appt with Bea I asked “why are we going to the appointment to be present for her?” I thought we were going to be there for Cee, to make sure that Bea wasn’t going to try and get chemo again.
Our roles as caregivers apparently changed without me knowing it. If there was a conversation about Bea taking charge and us backing away, I wasn’t included in it. If there was, I wanted to be included in on it, not just told as an after thought and accused of doing something wrong when I didn’t know that the landscape had changed. I was only trying to support Bea. And as far as I knew she was still in denial about the chemo and the disease.So where do I go from here? What are the next steps to begin communicating better with this overemotional sister (Essy) so that I can be treated with kindness, respect and as a caring member of my sister Bea’s team – not an outsider