Any suggestion on dealing with a bi polar sibling?

For the past five years I have been the caregiver for my sister, Anne. During this time I had to work with my 78 year old mother and a younger sister Sue as they both were out of state and would visit from time to time. Over time the fighting became unreal. Somehow I got through it. Two weeks ago Anne died. After 30 months on hospice she finally escaped her failing body. While I grieve for her long suffering and miss the vital funny being that she was before she became so ill, I would not have wished her to stay one minute more in her worn out body. It was a gift that I could help her in her final years.

Sue refers to herself as a fighter and in a meeting once told the hospice folks that we are fighters and nothing would change that. My question was , 'who's we?'...in my head. It got so hospice would not return calls because they did not want to be caught in the middle.

Sue argued in the funeral directors office, fought about funeral details and now is fighting about the estate. While she fights the process she seems unable to organize or follow a time line of how events actually happened. She forgets conversations, can not recall things that she agreed to and when she feels cornered becomes livid, reciting a repertoire of her view of me as a person. These spoken words are identical to tirades that she has written to me in emails. It was strange enough when she wrote them but when I saw her go into it in person I just didn't know what to say. It was frightening.

Here's the kicker, Sue works at a hospital that just got a new CAT scan machine. The employees were asked to volunteer if they wanted a free scan. She took them up on it because she has always worried that she might have the same disease as Anne (spino cerebellar ataxia) and wanted to make sure that her cerebellum was OK.

Last week she got a call from the neurologist. He asked her if she was having any neurological symptoms. First he was talking MS but basically he was thinking that the person who went with this test result must be symptomatic. After looking at the scan herself Sue has decided that it looks like a scan from someone with bi polar/ depression. She will have more tests to determine the actual cause, if possible. She is currently being treated for depression. For a long time I thought she suffered from Borderline personality disorder.

Long story short Sue has always had mental health issues. She is high functioning at her profession but a wreck in her personal life. The symptoms seemed to get worse with the stress of Anne being sick. Anne's death and the activities around that seem to have amplified Sues problems which I feel are verging on out of control.

If you have any tips or techniques that may work to help me understand what she is going through or ways that I can work with her more effectively I would love to hear them. I am not looking for diagnosis.

I am sorry this is so long but am thankful for any input that you may have. Peace, Kim