I know this issue has been explored before on this website, and I know intellectually that the answer is, probably, no. I just want to get other people's experiences and opinions to back my decision.
My mom has not been coping well at all with my dad's death two years ago come August 23rd. I found out through my cousin that mom's sister, whom she rarely calls because she can't hear on the phone and doesn't know what to say, has lung cancer that spread to her liver and has only a few weeks to live. She will be receiving hospice/palliative care at home.
Mom's condition has deteriorated significantly over the last few months, and I made the mistake of taking out dad's bed to give her more room, and put down a carpet to fill the extra space. She agreed at first, but since then she has been waking up not knowing where she is, who she is, what room she is in; and every time she goes into the room she gets a shock and a bad feeling. She fell out of bed one morning and bruised the side of her face near the eye, but didn't lose consciousness. Now I wish I had gotten her checked out. Her world was turned upside down when my brother wanted my sister to drive us out to his new house, about 3 hours away. Throughout the drive, she had no idea where she was going, thought she was going to see my brother in the hospital, claimed no one told her we were going to my brother's place, this is a long way to come for groceries, thought we lived in Liverpool and we would be travelling to the train station. She doesn't have the strength to support her body weight and gets breathless and feels like she's going to "drop" when she does any physical exertion. I have an appointment with her g.p. this coming week to make sure she doesn't have a urinary tract infection. However, I believe it is the progression of the disease.
My sister and brother agree that it would be cruel to tell mom that her sister is dying, since she would not be able to cognitively understand what's happening and has not seen her sister for many years. I'm wondering if, on some level, she senses what is happening and that's why she's feeling more anxious and unsettled. On the other hand, what about her right to know a member of her family has died? Although there is no way she would come across that information except accidentally. She still thinks dad is in the room and she's seen him and talked to him but she says she can't see his face. Hallucinations or spirit - who am I to say?
The way I see it, if she can't remember that she just had lunch/dinner; if she is now having trouble recognizing common surroundings (even the living room looked strange to her and she asks have we always lived her, or will think we just moved); if she can't deal with change and the loss of her husband; has unresolved grief over multiple losses as early as childhood; then I don't think I would be doing her any good by telling her that her sister is dying.