Wow, she spread your diagnosis? That is NOT okay.

You're definitely between a rock and a hard place right now.

I'm not sure what to say because you've tried handling your sister for a while now and it sounds like she's not going to change.

Have you told your sister that you want to cut her off because of her behavior? Or did you just cut her off without telling her? If it's the latter, can you tell her that she needs to decide what she wants to do? Tell her you'll give her time to think long and hard about her decision.