It’s ridiculous to expect being NC with a. Sibling and for it to have no impact on other relationships.
Being NC, you have no right to information about them.
They couldn’t tell you they were all coming to town that weekend because it would have been ‘we are coming to town that weekend, would love to see you. But we can’t see you Saturday only Sunday’.
Or what if they needed to get back and didn’t have time to see you at all ‘we are town next weekend but don’t have time to see you’. Why would they tell you that?
That would, inevitably, led to questions from you and you feelings left our. Either you would have realised why they couldn’t or assumed they were doing something else they were leaving you out from.
Frankly it’s easier, to just not tell you at all. And you don’t have a right to know. Their relationship with the sibling is now entirely separate to the one they have with you.
This was 2 years ago and you are posting like it actually happened last week. You seem to have very big reactions to things. I would guess they didn’t really want to deal with that either, when the weekend was about a sibling you don’t speak to.
and your sexist comment about how men are better than women, is ridiculous. Women are not obliged to indulge, agree or baby you because are also a woman.