If the aunt just wants the weekend, that seems reasonable. There should be no stressing on your break. Seeing as you have 5 weeks off, it seems reasonable to go to the aunts for the weekend. Speak to your parents, I’m sure they’ll understand.
I did not fully understand your post but maybe you can tell your husband how excited your siblings are about you two visiting the town and have made plans for a weekend or two for some family fun.
I dont know how important the aunt is and why he he chose to live at hers over instead of your parents especially when your family is excited about your visit.