
WTH?!!? I feel like I have entered a twilight zone...You jump on the wife yet have nothing for DH? I agree marriage is definitely about compromise but sometimes one side has to give in to the other. If she feels the relationship with the aunt is strong and close, why shouldn't she cancel and DH support her? She said "much to my dismay" showing a close relationship.
When it comes to illness or death--no damn vacation is that important--especially when it has been rescheduled only three months from now.
OP, wishing you support as you go through this tough time with your aunt.