Cancer with a brain injury

I have posted on this site before and I am reaching out now to see if anyone has a loved one who is dying from cancer and also has a traumatic brain injury. My sister is 59 years old and looks like she is already dead and she will not accept that she can't live alone. She has fallen twice that we know of. Once in front of me and once in front of my Dad and I'm afraid that we will become sick from heartbreak and worry. We check on her and I am begging for help from certain agencies today but I know they can't just take her off my hands. In addition to all that I realize that I am not equipped at all for this type of emotional toll. I have learned that about myself despite the fact that before this happened I thought of myself as strong and competent. I am functioning but it is becoming more of a struggle. Prayers aren't helping me much and I'm trying to go see my counselor today to unload some of my burden. Why can't I get a grip and realize this is part of life and before long she will be gone and I will know I did all I could? I'm bereft.