Welcome to HealingWell and to the bipolar board. I hope we can give you a little help.
You are in a tricky situation with your sister. You have to understand that when she makes decisions, she's not always making them with 100% a clear head. She is responsible for her decisions, to some extent, but she has a disorder that distorts reality and makes everything feel much more emotional and impossible than it really is.
You can't be her sole caretaker -- she needs some professional support as well. I assume she sees a doctor and stays on her medical regimen? Does she see a therapist as well? I'd really recommend it. The therapist can help talk her through some of the scarier, more intimidating parts of life -- like paying bills. If it seems like a therapist is out of your price range, most towns have a mental health clinic that charges patients on a sliding scale.
You also could use some professional support to help you learn how to deal most effectively with your sister. I also recommend a book, "The Bipolar Disorder Survival Guide" by David Miklowitz, to help you learn to deal with her bp.
In the meantime, don't offer her a loan. She's already turned it down. Move on, and if she asks for it, let her come to you. She'll figure out the problem is real and deal with it on her ownl
Co-Moderator, Bipolar Forum