Hi Marley,
This is really difficult for you and It sounds like you could do with someone to talk through how you are feeling and how to find a way forward for you to help your sister.
The Icarus Trust is a charity who supports people in situations like yourself. We have trained volunteers called family Friends who you would be able to talk to and may be able to help you. They would also be able to put you in touch with any other support you may want.
This is a free service and I hope that you would find it useful.
Good luck.
