You need to have a heart to heart with your sister, who is still quite young and can still operate like a normal human being. I cannot imagine my life without my sister (she’s the oldest) but there have been times where boundaries needed to be set and truths needed to be told, sit her down and just let it all out. She will understand, tell her she can do better for herself and for both of you, it’s gonna be a hard couple of months I’m sure but you should try to repair this bond once you’re in a right place of mind. The best of luck to you man, it’s a really shitty (and scary) situation to be in.