You say that both you and your hsband have been ill and that you were invited to the party and decided not to go. Maybe your family thought that they were being kind, not forcing you to decide about the holiday and that the party might be more manageable.
Whatever is the case, they are quite entitled to make their own arragements without any reference to you. You made a choice not to go to the party as it is some distance, so cannot blame them for that. Two week isn't very short notice.
Perhaps they wanted a holiday without the worry of two poorly people in tow, and cetainly your sister seems to think that you could not have afforded it anyway and did not want to put you in that position either.
What would make you feel better?
It sounds a bit like other people have been trying to be considerate and you haven't appreciated their efforts, they have obviously not made the choices you would have wanted them to make. They may have made clumsy efforts but they did have a right to suit themselves.
Your brother sounds like a lot of men, uncomplicated and happy to carry on being in touch, why do you hold him less responsible than your sister?
Men do seem to engage less and escape unscathed more often than women.
I would try to keep things cordial with both because they are your family and not evry family is the 'Waltons' in fact most are a bit fractured but family nonetheless.
Children holidaying during term time.
Cross partyAsylum seekers in UK should have right to work after six months!