Going to try to keep this brief but would appreciate advice...
A year ago, my DM told me that she and DF had been having problems (they have been married over 40 years, most of them pretty happily). She told me this on the phone the day after my wedding to DH (we went away for a very quiet wedding, just us, no family or friends), said she had not wanted to say anything, but I asked her what was wrong as she sounded upset, and then it all came spilling out - DF had a "relationship" (not sexual apparently) with another woman and was refusing to stop seeing her and there were other issues too around DM's health and DF's suspected aspergers which they have only just discovered and which DM seemed to think "changed everything". The gist of it was that she didn't think she was going to stay with him but didn't know what else to do, and this really rocked me, especially hearing all this the day after my wedding - took the shine off the whole wedding week but that's another story.
From then on, DM took to phoning weekly with updates and this is where the problems begun for me. She went into a lot of detail about things I was uncomfortable hearing about - basically saying a lot of things about my dad that affected the way I saw him and made me feel like my relationship with him was changing, but he didn't know she was telling me this and she wanted me not to tell him she had been talking to me. I found this grossly unfair towards my DF and after a few months of it, I sent her a long heartfelt email to say that I couldn't be impartial about this as he was my dad and I wanted her to tell him she had been speaking to me, and then to find someone else to speak to who could be exclusively on her side as it was so hard for me to hear a) such negative things about my dad and b) her side of it all but not his. (He is not the type who would really talk to anyone about it). She did apologise, told him, he acknowledged to me that she had told him, then she stopped talking to me about it.
However... recently she has started to tell me things about him again, they went and did something together a couple of weeks ago and afterwards on the phone to me she told me that he had shouted at her and was cross when she couldn't do it straight away and how upsetting that was. Now, I sympathise with her (he used to treat me like this too and it has had pretty long term effects on my self esteem and over-high expectations of myself) but the trouble is that yet again I am hearing negative things about my DF from my DM and it feels like I am being turned against him. Not on purpose, I don't think she would do that, but I don't think she realises that is actually the effect it's having and it's not fair as he is not getting the chance to put across his side of the story (nor would he, even if I asked him). In any other situation, I would have more allegiance to one party than the other and would not have a problem being a listening ear but this just doesn't feel appropriate as they are both my parents and I love them both and feel I owe them equal repsect.
So as not to spoon feed, DPs live 2 hrs away so I don't see them very much, have seen DM on her own only once since this began and the whole topic was studiously avoided. Also, I would say I am also on the autistic spectrum, although not as much as DF. I see things in black and white and have difficulty accepting shades of grey and this could be one of those cases where it just can't be black and white and that might be why it is making me so frustrated. Also, I strive to make things fair, and I am very loyal, particularly when I feel someone (in this case, my DF) is not being treated completely fairly or a situation is unjust. Lastly, I am not the best at empathy and my relationship with DPs is not a very close one, affection did not abound in our household when I was growing up and I never felt loved unconditionally, just pushed to achieve more and more). All of these things could be contributing factors to how I am feeling about this and could be stopping me from seeing the wood for the trees which is why I genuinely cannot work out if I should ask DM to stop this or whether that would be mean of me.
So, I'm opening the case to the mumsnet jury: AIBU to ask her to stop telling me negative things about my DF, and to explain why (again), or should I shut up and listen to these negative things about my dad with a sympathetic ear as she is my mum?