MNHQ tend to leave this sort of thread up in Night Watch, and I hope that they will this time. It helps to highlight to us all what unfortunately can happen and how to deal with it.
Unless it's a glaringly obvious troll, where I think a bit of calling out on the thread, often with great humour, is ok, I think it's always best to just report the thread to MNHQ and start a thread here to alert our Night Watch volunteers if out of hours.
When I read the OP, my spidey senses started tingling. I think because I was caught out by a similar troll once, I am well aware it goes on and it's made me more cautious. In that case, it was about a late term miscarriage - similarly heartrending - and the writing style of last night's OP reminded me of that. Something didn't feel right about it.
I couldn't be absolutely certain however, because in my own experience terminally ill mums have done things like writing cards ready for years ahead, and loved ones have been 'with it' in some cases until quite close to the end in hospices, hospitals and home. People do namechange and people do come on here at the very worst of times seeking support. I didn't want to make the dreadful mistake of denying support to a genuine poster, which is why I chose to do what MNHQ ask us to do - report rather than question the poster.
It is dreadful, and often quite shocking and upsetting, that people make these things up, but it's a sad fact of the internet and of life. I feel sorry for them, more than anything. We just have to try to make sure it doesn't prevent genuine posters from seeking and receiving the support they need.