Kind of the opposite, I said something completely horrible to somebody yesterday which is worse than anything I've ever said or even heard in my life.

I'm in high school and was at lunch sitting with a group of about four friends. To my left was a friend and to his left was somebody who I'm somewhat acquaintanced with, but not chummy with him. Let's call him Chris (because that's his name). He was doing his own thing, probably not actively listening to the conversation, but still in hearing range. Short background info: a few people have heard Chris' dad speaking of him beating Chris, things like "And they wonder why I hit him." We were talking about God knows what and got on the topic of beating. Being the dumbass I am and forgetting he is there, I instinctively mumbled "doesn't Chris' dad beat him?" Some were quiet, some started saying "yes" but cut themselves short. Someone mumbled, barely audible, "he's right there." He didn't make any acknowledgement of hearing what I said, but I know it was loud enough that once his name was said (because I said Chris' dad) he would hear the following sentence. I instantly felt and still feel like a total jackass. I have no clue if he heard me, so I didn't even apologize. He didn't say a word and continued doing what he was doing (he was acting the exact same as before). I just sat in silence for the next 20 minutes until the period ended, thankfully did not have to face him in any classes, and ended the school year like that, avoiding the horrible thing I said for the next two months. I'm quite surprise that, assuming he did hear it, he didn't walk away or respond. I sure as hell would have walked away and sat somewhere else.

I know what I did was wrong, way worse than wrong. Today I want to apologize profusely for it.

TLDR I mentioned somebody's dad beats him, which is supposed to be secret and kept to himself only, right in front of his face and didn't apologize. To answer the second part of the question, he just sat in silence.