It's Mother's Day in the US. Came across your post and had to reply.
My mother committed suicide at the age of 60. She chose a violent exit, which is uncommon with women. She did have a mood disorder which had been successfully controlled for years. Or so we thought.
What my brother and I didn't know was that she had actually tried, years before, with sleeping pills. She asked my dad to hide it from us out of embarrassment and guilt.
I don't blame my dad, but wish I had been told, because when he told me (I live out of state) that she was losing weight, had issues sleeping, complained of a constantly upset stomach, I would have considered those big red flags. I would have come to her immediately and seen she was truly not in her right mind. As I'd just had a miscarriage, I simply tried to call her more often and assumed she would reach out and get help as she had always done.
Not so.
The reason I bring this last bit up is because I'm wondering about your daughters. If they have been talking about suicide, might this not be a good reason to tell them? Let them see how gutted you are?
I don't see how you're going to hide your anxiety, guilt (?), anger, and distrust of your mother. (I can't see how you are doing it right now!) My teenager would definitely notice and wonder, "And all this b/c Nana had a fall...Is Mom losing it?"
My son and daughter know about my mother. My son was only three when it happened, and my daughter was not born, but as soon as they were old enough to ask questions, I answered as "age-appropriately" as I could. And not without a frank discussion about how deeply this has affected me and my family. I'm not positive, but I think they are (hopefully) "inoculated" against trying such a thing. Depression and suicide are now an open conversation. Not pushing this, of course, you know your daughters best.
Just another perspective.
I'm so sorry.
BTW - the social worker's question was completely out of line!