AITA for throwing a cupcake in my nephews face after he humiliated me

I (16f) have a nephew (12m) who is a constant asshole and he always has been. He is not autistic or anything, he just fucking loves hurting people. He picks on everyone. I have talked with my parents and they have talked with my sister and none of it has really changed anything. He is truly like the boy from the movie Matilda.<br><br>He is my sisters only child and so he gets spoiled. He is always getting allowed to pick where to eat or what to do, and he always picks things that he knows annoy others. For example, he knows that I hate kfc but he always demands to go there because I don’t like it. <br><br>So my sister is getting married and it was still an open question whether they would delay it due to corona or not. So we all went to a restaurant to discuss it. They decided we would still have some wedding stuff but it would be at my sister and her fiance’s home. I went to go to the car to get something and as I was walking outside of the restaurant, I accidentally slipped and dropped my drink. It spilled all over my pants so I had to go to the bathroom to clean it.<br><br>I came back and everyone went silent. I asked if I had interrupted something and they all started talking at once, but I couldn’t make out much of what anyone was saying. I asked my nephew to slow down and he goes “oh this doesn’t concern you anyway.” I was pissed tbuh so I went to go back to my original seat. My nephew said “see? I told you she was weak.” <br><br>I asked my sister what was going on and she explained that my dad called my nephew gay and he got mad. My dad was apologizing but also saying he was just joking. I didn’t really care about it at all. I was just mad my nephew was being assholey. So I jokingly go “oh yeah, you’re gay as hell. I’m not surprised. That’s why no one likes you after all.”<br><br>He just goes “you’re a bitch” so I go “no I’m not. I’m not the one who gets called a pansy.” He goes “I’m not gay so idc about being called that.” So I go “how are you not gay? You have a vagina for a mouth” (this is something my dad always says to my brother and it always makes my nephew angry. Idk why)<br><br>He asked why I was being so mean to him and I go “you’re mean to everyone so fuck yourself” and he just gets up and runs to the car crying. I came to the car afterwards with my parents and sister and my parents go into a lecture about how I’m mean. I interrupted and go “he’s always calling me a bitch” and my parents go “well stop being mean”<br><br>I go “I fucking hate him. He’s such a dickhead. I’m going to make his life miserable” and my sister goes “he’s just a kid” and I go “yeah but he’s an asshole and everyone hates him” and my sister goes “I don’t hate him” and I go “why the fuck not? He’s so horrible to everyone. It’s not like he doesn’t deserve it” <br><br>She just started crying and my dad had me wait in the car. I was called back inside afterwards and they were scolding me for hurting my nephews feelings and I interrupted them and go “but that’s ok when he does it?” And they go “no. But he’s a little boy and he doesn’t know any better” <br><br>And I’m like “you know this is the reason I hang out less. You know he’s an asshole but you never punished him for it” and they just told me not to talk like that. They told me to just ignore him when he’s mean to me. But I’m not gonna ignore it. I’m 16 and I’m much more capable of sticking up for myself than I was when I was 9.<br><br>My parents go “if you can’t be nice to your nephew then you have to go home. This is your sisters wedding and she doesn’t want you ruining it” so I go “what do you mean I will ruin it? I was invited” and they go “but not if you’re going to be mean to your nephew” <br><br>So I go to the car and my sister and fiance are in the car talking to my nephew so I go to my parents car and I drive home. I get home and I text my parents and go “I’m never going to the wedding if he’s invited” and they just say “that’s fine. We will pick up your things and you don’t have to come home until after the wedding is over with”<br><br>I go “why are you defending him? He is the one who started the shit” and they go “he is just a kid. You should have been sweeter to him” and I go “I’m not being sweet to him. I’m not cleaning up after him anymore. I’m not going to go out of my way to be nice” <br><br>So my grandma calls me. I didn’t call her. My parents must have called her. She was talking about how I was being immature and I go “no. I’m fucking fed up. I am sick of him ruining my life and I am sick of you all defending him and making excuses for him. I’m done being the villain. He is the fucking villain”<br><br>She goes “but he’s a child” and I go “oh my god, stop. He is not an innocent child. He is an asshole who loves being shitty. He will never stop” and she goes “well he will stop if you are nice to him” <br><br>I go “I’ve been nice to him for years. It doesn’t fucking help” and she goes “but you should be nice because he is your only nephew” and I go “I don’t give a fuck if I don’t have a nephew. I hate him that much” <br><br>And then she goes “oh my. You are so fucking rude. I hate that your father raised you” and I go “fuck you. I’m not the one who defends assholes” and my grandma goes “fuck off then. You’re ungrateful”<br><br>And she hung up. <br><br>This was all on Friday. On Saturday my parents told me that my nephew was crying in his sleep and vomiting all night. This morning, my sister calls and tells me she’s not getting married because “I ruined her wedding stress and everyone’s starting to think her son is too much to handle. They talked last night and she asked if he wanted to postpone because of my behavior and he said yes. It’s not worth it if her son is going to be so stressed out about the wedding” <br><br>I go “but this isn’t even my fault. He’s the one who was being mean and he’s the one who ruined everything. Why are you blaming me?” <br><br>And she just says “I’m not blaming you. I just don’t want to have my wedding with you there because I know you will ruin it” and I’m like “why the fuck does everyone keep saying that I ruined things? He started shit but no one fucking cares. No one cares that I was just defending myself. You all are so fucking unfair and you always have been. You always defend him and never punished him for shit and now you are all upset because I wasn’t being nice to him? Fuck off” <br><br>And she goes “fuck off then. If you’re not gonna be nice then you can just fuck off” <br><br>And she hung up. <br><br>I feel like everyone is blaming me for this and everyone is fucking wrong.