Hi Custardo, not read the rest of the replies so sorry if I repeat anything.
As you know - I didn't speak to my mother or father for over two years. My mum is also barmy, barmy, barmy (alcoholic + suspected bipolar)
Then, out of the blue, I received a phone call from my father and a Christmas card. I decided that for my own sake I'd just let it go. My father demanded that I see them, playing the "we are getting old and you'll never forgive yourself is something happens" card.
I now maintain polite contact with my parents, mostly so that if something does happen to them, then I won't spend the rest of my life feeling guilty (as I do about everything, rightly or wrongly).
You know what - during the 2.5 years I didnt speak to my parents I regained control. I realised that they cannot hurt me or control me and that underneath they are human too. Contact with them is now not stressful for me because I maintain my distance. I will not be seeing them personally (we speak on the phone and email) because I just can't deal with them.
I suppose my long and rambly point is, is that you need to be sure that contact with your mother won't be detrimental to you. If you are sure you have let go enough to be able to walk away if she starts on one again, then go for it. Otherwise a distant phone/mail relationship might be better for you in the long run.
FWIW I think the fact that she brought your kids into is terrible. That is something I would find very hard to forgive - my own mother constantly told me what a crap mother but never, ever dared bring my kids into it.