AITA for choosing my BF over my dads family because of his wife?

SM: step-momBackstory: My dad remarried into a large family around 20 years ago but I've never felt comfortable with SM or her family so I hated the holidays since I was a child. SM also hates my long term BF (9 years).SM claims my BF decided to try to kill a bee years ago. She had mentioned that its only a bee and to leave it alone because its just coming to drink water but my BF just laughed it off. SM got mad because he disrespected her in her home. SM then waited 4 years to tell dad about this. By then, I knew my BF long enough to know it was either a misunderstanding or possibly a lie on her part (Bf is not like that). She still held a grudge years later and I recently found out that anytime BF and I came over my she would snap and yell at dad after we left.Thanksgiving my SM yelled at my dad because my boyfriend had gotten annoyed with her since SM force us to play a game when we didn't want to. I had gotten annoyed too but SM had made a snarky comment to him about being a pissed and he had enough of her negative comments. (I don't remember exactly how he said it but the gist was "if you want us to be happy maybe you shouldn't force us to do something we don't want")That Xmas, I bought my family presents while my BF bought his family presents and we just said all the presents were from us. That year I bought SM a decorative leash holder that I thought looked really cute. It was a wall hanger of the back end of a weiner dog and below it said "wag more, bark less". I knew she was a dog person and I thought it looked adorable so I bought it. Xmas night she screamed at my dad telling him to throw away my gift to her because my BF was telling her to "shut up and nod bitch" with the saying on the leash holder. She then told my dad my BF was no longer invited to any of our family get-togethers.My father told me this and I broke down and got angry. I told him the gift was purely my decision and I got it just because it was cute. He said my bf was not invited back until my bf worked things out with SM. I told my father that I wasn't going to any events if my bf wasn't going to come. I said I was never comfortable with SM and her judging family and never felt like I belonged there anyways.My concern: Two years later my father and my birthday is on Thanksgiving day this year. I am still not going to Thanksgiving dinner but I may or may not stop by during the day. I don't expect him to leave his wife at home if I invite him over and I am not going to go alone and let her family constantly ask where BF is. If this were to happen, I'd want to be petty and tell them SM dis-invited him. I'm chosing not to go for my sanity and not create drama on the holidays. I know my dad misses seeing me on the holidays and he was always the only happy thing when I spent holidays with her family.AITA? via /r/AmItheAsshole https://ift.tt/3oL4fzW