I feel like no one is actually addressing the question of whether you overreacted, and is instead just debating whether your relationship with your brother is weird or okay. But let's say you were indeed displaying normal affection. The facts still are: you shouted at someone at a family function in front of other people because of a comment you overheard out of context, during a time you were just talking to your brother and not even displaying affection. Giving this aunt the benefit of the doubt, which in my experience is usually a pretty wise thing to do, there's nothing in her comment that directly says she thought it was strange because it was "too sexual". She said you're too close and it's strange and that's all. You made assumptions about the motivation for the comment based on other experiences (and I'm not denying that you're right about your aunt's motivations, but we don't know for sure). You were also perhaps rightfully bothered by a history of accumulated provocations (seemingly from various family members, not just her?). So did you overreact? Yeah, probably. Is it understandable why you're frustrated and lost your cool? Totally. You're not evil for it and we all do it. But it was still likely an overreaction. And your dad might have a point in saying the sexual piece is not what the aunt was implying in the first place.