I've really had it! I'm finally disowning my sister
Really, your sister? What motivated you to disown your sister?
I'm tired of taking care of her and I'm tired of giving money.
I'm sorry that your sister is causing these issues for you, but you shouldn't disown her. It sounds like she needs you very much. Instead of disowning her, try to help her become independent.
I have no more time to give her any support.
I completely understand the frustration. Would it be possible to find her some type of program that could help her learn to succeed? She would learn to be independent, and you would get a much needed break.