I wish I had taken all of the money I gave my freeloading mother, who also thought I should take care of her. Abusive mother I should add. And you know what I would spend it on? MY daughters student DEBT!!
You have others that need your resources and you have done enough. She is your sister NOT your child or parent. She needs to stand on her own two feet. Get that house SOLD or rented to someone who will PAY THEIR RENT and then your sister will have some money for a fresh start when you tell her you are done!