awww pruni you poor thing. Don't think it helps if your mother is drunk often either - the drink encourages them to be more emotional and confrontational and brings out all the 'oooooh I was never given a chance' blah blah blah sort of rant.
The problem is you can't just ignore it because they are right there! And as much as I agree with the 'creating distance' thing, it's very difficult to suddenly cut an emotional bond especially when you've been the adult in the relationship from a very young age!
I would second therapy (not that I've gone myself, ahem) but have heard it works wonders when you get the right therapist. Just get yourself on a NHS waiting list then forget about it till your place comes up.
But yes, I do sympathise terribly with having mad parents and horrid conversations about stuff that you REALLY don't want to hear anymore! And there's a thread somewhere in relationships about mad mothers - have a feeling you'd fit right in .