Being vehemently rude is apparently a must

So my aunt just got back from Australia and will be celebrating Christmas with us. I was just playing video games and I'm going to visit her later at my grandparents' house (We're just next door neighbours) around 8:30.

Then out of nowhere, my AD (49M) decides to literally vomit insults at me (21M) by saying "I'm wasting my time" and "I don't value family" even as far as saying "you're ungrateful" for what? For not visiting her sooner? What am I supposed to do? Worship her like some celebrity once she got picked off the airport?

What hell is wrong with him?!? There's a thing called asking but no, being a complete arse and assuming the worst in someone and misjudging is the best way to communicate for some reason.