I'd be very upset, too, so do understand perfectly how you feel.
I dare say it upsets you a lot more than it does your dds or Gdcs though - you naturally feel so hurt on their behalf, more so than if it were you she was leaving out.
After your previous falling out, maybe she is purposely doing it to upset you, as a pp suggested. Whatever, though, I would let it go, don't rub it in that she's upsetting you, since if that's what she's aiming for, she'll have achieved her purpose.
There's surely nothing more irritating for anyone trying to upset you than a serene smile, as if you haven't even noticed!