I'm glad your wife got diagnosed and hopefully the lithium is kicking in. It's almost impossible to keep someone against their will more than two weeks; the way the case law has evolved, if you're capable of eating out of dumpsters and sleeping under a bridge they'll let you out.
Don't take anything personally and don't feel like you have to do anything right now. You can't really tell anything about your relationship until she returns to sanity. Don't mess with her finances but it's ok to not be in a rush to return her credit card.
Your sister can just say you're doing ok. She should avoid relationship discussions with your W for now. It's awfully good of her to take your W in like this. Do what you can to support her recovery behind the scenes, but stay out of the way. And keep focusing on creating your best life, as you have no guarantee that when she returns to sanity she'll come back to the marriage. She may, or she may not. Just stick to the high road and give her some space.
