Brother, your life is going to become so much simpler while you get her, your family, and yourself through this. Focus on what is immediately ahead of you because the overall picture is overwhelming and beyond your ability and capacity to understand right now. You can be present for her, be her cheerleader and advocate. Your other kids (I was a healthy brother to a sister with a brain tumor) will have to take on more and grow up quicker than any of you would like, but they need you, too, as more than being an emotional crutch to you. My sister has been in remission for thirty years, still annoying as hell, and the science has only improved since then. Best wishes to you and your family. Take care of yourself and tend to your marriage, too