Echoing the others IncessantNameChanger you don't have to become your mum's carer, given how she is I'm surprised you're still in contact. You can choose to be in contact on your terms, your mum, sister and anyone else can't make you be her carer, just say no. You don't even need to give anyone a reason why, "it's not possible" is reason enough. If you start giving specifics people will start arguing why they think you're wrong and that's a waste of your time to hear it.
I found a few more things to let go of over the past week.
Two pillowcases which I no longer have the duvet cover for and they don't match any of the others or the bedroom decor. Quite hard letting go of something that has absolutely nothing wrong with it, but I didn't buy nice things so that I could keep on using unsuitable things.
A lovely jumper that's in excellent condition and a lovely colour but is a fraction too small. Every time I wear it I'm annoyed by it riding up all the time and I'm constantly pulling down the sleeves too.
Had to find my sunglasses, we've had some perfect weather, binned the case which was disintegrating.