Very briefly, I have supported my sister financially for several years - she lived with me rent & bill free for 6 months, then moved into a rental house I owned for 2 1/2 years, at a massively reduced rate - (didn't even cover the mortgage, but I didn't mind, out of family loyalty).
I helped her to buy a house, and she moved out of my rental house - and left it in a complete mess. I have been in property rental for 13 years, and have never had one of my properties left like this - it was horrendous. I phoned her and asked her if she could help me to clean it. My DD was a few weeks old, I had had a very traumatic birth, and had severe injuries from it. Instead she arrived at my house and screamed at me to go fuck myself. hmm
Since then, she has ranted at anyone who will listen about how dreadfully I behaved towards her. She is not above inventing complete lies in order to justify her dislike towards me.
Blue Sky
Was wondering exactly why you did help her in such a manner, were you obligated to as well by your parents putting pressure on you to do so?. Did you for instance have your parents saying, "oh we don't know what to do with her?". Were you told by them to "rescue" her and "help her out"?. Your sister seems like both an irresponsible and very troubled individual but you are not her responsibility ultimately. I think she threw your kindnesses back in your face and you yourself learnt a very harsh lesson in that enabling does not help the one being helped.
I reckon as well she has always been like this and both your parents have played a large part in shaping her behaviours as well. How are they towards her and you?. You're seemingly the scapegoat for all the toxic stuff in your family aren't you?. Children now adults of toxic families often have defined roles. The "stately homes" thread would be a good one for you to read and even post on. You will get support there.
I would also suggest counselling for your own self as you need a neutral person to help you with the understandable anger and resentment you feel.
TBH I would distance myself completely from all of them including your parents (do they also run around after your sister as well?) and concentrate instead on making your own family life a good one. Living well is the best revenge.
You would not let a friend treat you in such a manner so why are family members any different?. They should receive no special consideration just because they are "family".