Which ended with DD in floods of tears, past bed time for over an hour last night & I of course had to mop up the mess 
Genuinely not sure if I'm over reacting, as I do have a very difficult relationship with my DM, no coincidence I live at the opposite end of the country :(,
she is pretty narcissistic to put it mildly & I've grown up mopping her brow over one hurt/illness or another, things like attempted suicide when I was 8 & my having to get her help ?after leaving home I had monthly phone calls where I was up all night talking her out of topping herself ..& then get up for work ?..
this and LOTS more has meant that in my in my old age become pretty fed up of doing so, so we often go for long stretches of her not speaking to me, because these days I tend to tell her straight & she throws a strop & I'm evil & cut off for months on end ?for example ?recently their Cat died of kidney cancer - so DM now has convinced herself she has kidney Cancer
She does have some pretty serious health problems, which on their own are enough & she uses to best effect :( so basically I've become fed up of been the adult & counsellor in our relationship, & though love her to bits, for my own sanity I just don't tolerate it any more, so I am aware I might genuinely be over reacting..
Story as follows...
I put DD on the phone to DM last night - DD was already in bed so it was meant to be a short "goodnight" chat - DD was practically falling asleep on the phone & hardly said 2 words - it is often hard to get a word in sideways with my DM, & I kept trying to coax DD to say good night & get off the phone - without being heard or I'll be evil witch again 
Anyway turns out DMs conversation with DD (who is barely 9) was by way of telling her all about their Cat dying & how heartbroken DM was over is, DD tells me afterwards that this was pretty much all she talked about & when DD didn't say much back, DM then goes onto remind her of our own Cat who died last year, leaving DD heartbroken & thats how "Nana" feels now
so she should be really sad for her
I could see DD welling up, so took the phone from her, without knowing what the conversation was about - told DM that DD was tired & it was only meant to be a quick call to say goodnight - DM said, "well I thought I was keeping her awake for you, she needs cheering up & someone to talk to"
(DD is on crutches after a fall) - its gone 10 30 by now & shes been on the phone well over an hour 
Put the phone down myself to have DD break down into hysterics, sobbing her heart out over out old Cat & "Nanas Cat & everyone dying" she was inconsolable for nearly an hour 
Surely its not normal to expect a 9 yr old to have that sort of conversation at bedtime
if at all
AIBU to be fuming & wondering why the hell I ever bother with her at all??
Thanks :)