Dear Beth,
This withholding of important info is a slap in the face which I've felt, too. I'm so sorry you're being treated with such ongoing devaluation and disrespect by your parents. Hope your dad is better now!
Beth, I don't know whether this will apply to you, but for me... well, there are a couple things I sense.
First, no doubt I'd feel resentment about them placing undue preference on my sibling who's viewed as the competent, potent one. In my case, my brother is the one with both the bluster and the money to make a big show in response to something like this (not that he actually would respond, since he's so wrapped up in himself all the time). Anyhow, I'd probably find out long after the fact, and then only by some very vague and circuitous references which would be primarily focused on how very difficult this all was on my mother. (This has actually occurred, years ago.) So... seems to me you'd feel so much better in general if you choose to stop comparing yourself with how they treat your sister. That says SO much more about them than about you, Beth. You are no less valuable, important, special, skilled, powerful, necessary, etc, etc, etc than anyone else.
And then, there's the guilt. Again, I don't know about you, but I feel guilty when I'm the last to know, because I've had so many negative thoughts about these people and made it my own practice to NOT allow them within my safety zone. When something like this happens, there's an instant, reflexive reaction of feeling like it's my fault they are this way to me. If only I'd cozied up to them more, etc, etc. But that's a lie and you know it, eh? There's nothing you can do to make them into whole human beings who will treat you as you deserve to be treated. Best we can do with such folks is to teach them how to stop mistreating us by refusing to accept such treatment.
What if they hadn't notified your sister, either?
It'd be a whole different situation then, wouldn't it?
Also, seems like they only include folks in the loop whom they consider useful.
That doesn't make your sister more highly valued, just makes her a tool in their eyes.
Do you really want to be a tool to them?
With some folks, that's all anyone is, no matter who you are or what you can do.
((((((((((Beth))))))))))
Take good care of yourself.
With love,
Carolyn