I (18M) and my boyfriend (19M) have been in a relationship from the past 3 years. mind you, we have an open and healthy relationship and everybody knows about it. his family is very supporting, and mine is too. except my sister. she isn't homophobic technically, but loves to belittle me and him every chance she gets. recently, she apparently "changed", and was getting married to her boyfriend of 8 years. truth be told, her now husband is like my older brother and I was really conflicted about my decision. after all her assholery, I don't necessarily talk to/text her and the last time we had talked was around 6 months ago. BUT she suddenly starts to beg to everybody, telling them that I need to attend her wedding.I didn't want to, so I made up and excuse for ik that she hadnt really changed and would poke fun at me, she also didn't invite my bf, which is telling in of itself. now everyones on her side, saying that I ruined the wedding and that she was constantly sad throughout. I think that I was firm about my boundaries. so please tell me, AITA?