Thanks for all your continued comments.
Did start to document all the events, but it's lapsed when things appeared to improve. This behaviour has been constant for many years if I stop and think back. Going to college may have been the trigger when I changed from shy and malleable to having an opinion. Perhaps a therapist would help. Have challenged her or decided to keep quiet, but it's like poking a stick into an animal's cage; both stances annoy her.
Yes, have become unofficial nursemaid, who's expected to do personal tasks. Thankfully she's not incontinent but it's showering and washing that I'm afraid I just can't do. Even if I could, doubt whether she would have confidence to as shower is over bath. Think it's due to fact that for as long as I can remember she's been obsessed with medical matters, wanting to show me C-section and hysterectomy scars.
Earlier I remembered a former colleague who had aged parents. She often referred to "the kids". At first I thought it was her nieces and nephews, until one day I realised just who she was talking about. Sorry, but I did find it amusing, not realising then that I'd be experiencing the behaviour first-hand.
Thanks again, you've all given me food for thought...