Have found the relationships board very helpful, following others threads on here, have diagnosed my mother as a narc and it has actually helped with how I manage her. So thanks to all the wise posters for this!
I won't go into the long and complicated history but suffice to say she is selfish, self centred, a bully and generally emotionally manipulative. I went through a stage of distancing myself from her, visiting 1 -2 monthly but from about 15 years ago she has had health issues and so I helped more (hospital appointments, monthly shopping and lunch out etc). My 2 sisters live locally, I am an hour away. 1 sister visits/helps daily, the other 2 times a week and we generally just try and tolerate her unreasonable behaviour by doing a lot of hmm'ing when she is ranting! So we all muddled on until she was then vile, and said very nasty things about me in the lead up to my wedding a few years ago, I told her that her behaviour was not acceptable, she half apologised, came to the wedding but then spoilt parts of the day by behaving badly, refusing to eat/drink food and wine provided/being generally demanding/ being morose. I had to talk to her 3 times during the day and ask her not to be so negative/nasty and this was supposed to be a happy day, please could she try to be happy for just this day (I had asked her this prior to the wedding as well).
Since then I have remained a polite relationship with her, although she continues to shout down the phone at me for things like not weaning my DS earlier than 6 months or not phoning her enough (she tells me she can't afford to phone me - which isn't true she has plenty of money). I generally tell her I am not continuing the conversation if she is going to shout.
I am now planning my DS's christening and I just don't want her there. I have told my sisters, but they think I am being unreasonable and are making me feel guilty (of course I feel guilty but I just want 1 nice day that's not about her! It's such an important day for us and I don't want it ruined). My sister's don't really challenge her behaviour, and they think as she is so old and has ill health we should make her life as nice as possible and ignore her behaviour. But I am totally fed up of her, I think I would cut contact if it was not for my sisters, I certainly don't want her influence too much in my DS's life.
Sorry this is a long post. Would value advise.