I am!
It used to upset me a lot but after having counselling I'm ok with it, and see it as my mum and sister's problem rather than mine. If anything, these days I find the way they speak to me quite amusing, and I do limit the amount of time I spend with them and have very firm boundaries in place.
It's funny though that even though my sister and I are now in our thirties, my sister still keeps to her role as the 'favourite', and seems to almost get pleasure from speaking to me badly and with contempt.