To each their own opinion, but the way I see it.
She might be upset with herself for what happened, but loosing her sister for 1000 years would still be worse. She would have the love of those close to her to keep her alive. The ponies might panic at the drop of a hat but they recover just as fast once they know they aren't in danger anymore. It shouldn't take long for them to accept her new form.
As for the changelings... hard to say without knowing more. but I could see the next generation being treated as if they had done no wrong, since they haden't.