bobby, I am sorry about your Uncle and sister. She sounds really stressed and in a way feel honored that a big sis felt comfortable to let you be the sounding wall, because she needed the younger sis to be the big sis for her. I am sure she never thought about the extra concern it caused you as she is in overload.

Don't give up on hope and the love of others. I will pray for your Uncle, and tell him I am honored that in his family he gave me a dear friend. Next week I will volunteer at a local low income after school program near us in honor of your Uncle.
Maybe I can make it a family day for my family we will be together helping others and we honor your Uncle for all he did in life.

Send that note to your sis, something not expensive, just a joted note that she is a special person, and while she is stressed, to take time for herself, and know that you love her.
di