I don't think one "gets over" sisters, especially if they're still around. It is kind of like a divorce. Did you read this article on happiness http://psychcentral.com/news/2007/03...-on-happiness/ it says that not all events are created equal, some one doesn't "get over."

I'm glad your feelings don't last a day; that reminds me of some of my old dreams where I'd wake and be depressed because of them? I think it's probably inevitable when you're with these sisters that you're going to be "reminded" of whatever it is that upset you in the first place? Even just being around the niece and great niece without the grandmother would probably remind you of your sister? I don't think there's anything wrong with feeling sad things aren't or weren't different? I would actually feel badly if you didn't "care." It's hurts. It could get better with time but I don't think it has to necessarily; there's still hope.