Mizzuno, sounds like you are in a really difficult situation. Of course you're concerned, and don't want to do anything to wreck the relationship if it's just getting back on track. It is so hard to let it play out, I'm dealing with that with a friend and it's very scary.
I'm glad you have your brother and her husband with you to help make these kind of decisions. Hang in there, and know we are all sending you prayers and good thoughts for your family!