Patty, I think your reaction to your sister's unusual and distant behavior is very understandable. Her behavior isn't making sense to you. It's your reaction and there isn't a wrong or a right about it, in my opinion. I wonder if you wouldn't feel better getting to the bottom of it by talking directly with your sister and telling her that you sense her being vague and distant and it feels unusual and unsettling to you. Her behavior is, of course, about her; it's how she is dealing with.. something.

Her behavior sounds somewhat like my behavior when I am depressed and don't want to be a part of holidays or birthdays. Maybe what's going on is something in her life that she's struggling with?

It sounds like you were lonely and sad today. I'm sorry you didn't get to see your sweet aunt. I hope you feel better soon!