I wouldn't tell my aunt anything (unless she personally invites you, instead of just assuming you'll show up?) other than "I'm sorry, I already have other plans with some friends of mine" :-) I'd see, while at Thanksgiving if you can also hang out at the aunt's sister's for Christmas. To heck with the mother you don't like and who doesn't treat you either respectfully or even like she likes you. If she doesn't like you, I don't know where she gets off wanting you to come see her? Tell her you'd just be a "useless, stupid, mistaken, fat, ugly, retarded, dumb ***" blob if you came to see her so she shouldn't waste her time (or yours!).