OP, I am so sorry for you, it must be so horrible and difficult and painful, I am really sorry for your loss.
Please believe me that NOT every other mum thinks about her own child (in a "thank God it didnt happen to me"-way). Still, I think these mums could at least say: "sorry, I dont know what to say". Still, Yabu (a bit) for making a list of rules (that others are not aware of). Good idea: This thread, as it helps us understand what an appropriate reaction would be in a case like this.
I know a mum at school whos mother was dying, and who was (is) very upset about it. If I ask her how she is, she sometimes gets so overwhelmed she starts crying. Its hard to know what to do or say, other than showing that I know this must be a tough time for her, and that I will take her DD to my home on days she feels it`s all too much.
I do admit I sometimes just chat to her about the weather or holidays, even though I know she is grieving, as I think it might restore a sense of normality???
It`s not easy to know what to do or say, sometimes I can tell she wishes everyone would just leave her alone...
Wishing you strength,