I don’t think this actually has anything to do with you or your mom. His mom is jealous, and it sounds like her feelings are hurt that her expectations for the day were no longer being met (because she was expecting you guys to come to their dinner), which likely upset her… especially if you’ve always spent Thanksgivings at her house, she’d be expecting you guys to be there. She also may feel like her son is choosing you and your family over her and his family, which is sort of a hard thing for a mom, especially if she has a son that always made her a priority or always showed up to family events. As a mom, it’s hard to learn to let go, even when you should. So I am almost positive that’s where her comments are coming from. They aren’t actually directed toward you and your mom but it’s just a projection of her negative feelings about the situation.

I’m also not saying you guys are in the wrong at all for wanting to spend Thanksgiving at your mom’s. Your plan sounded reasonable, especially if you don’t see your uncle very often and it was a special thing for him to be there if he could’ve made it. But his mom’s reaction isn’t logical or based on reason, it’s emotional. So while you’re not wrong for feeling how you feel, I think if you look at it from her perspective and see why she might be upset (however unreasonable it looks from a logical/outsider standpoint), it sort of makes it a little less offensive because it’s an emotional reaction that’s really coming from her own issues with not wanting things to change and also not having expectations met. Know what I mean? I really doubt it has anything at all to do with you or your mom in any way.