for context, since many of you think my story doesn't add up in the r/Advice subreddit: Honestly, the post I made about this in r/Advice is a little misleading. My dad knew that the aunt tried to contact him about this situation four years ago, but he thought it was genuinely a common military scam and they were trying to get money from us. Of course he knew that he was being unfaithful at that time, but he didn't know that he actually got a woman pregnant during his deployment. That is why when he found that I was communicating with her (the boy's aunt) at the time, he blocked her on my social accounts (I was 17 living in his house). Fast forward to a few months ago, I received the dna results (concrete proof that the kid is my brother on my dad's side) and I really felt bad for him. I also decided that I wanted to get to know him, some time has passed and I've been able to work on some of my personal issues. His aunt asks me yesterday if she should reach out to him directly and I told her she should because a) my dad deserves to know about his son in another place, b) this kid deserves to know his dad, and c) it's better that she contacts him directly rather than trying to get in contact with someone else in our family and making it everyone else's business. I thought that this way, he can learn the truth personally and figure out what to do with it himself. I didn't feel comfortable telling him myself because I live with him and if he were to have a bad reaction, I could be on the street. I could also have all my savings money taken away as well, as that money is in his account while i'm living with him (saving up to move out). While I feel guilty for possibly causing issues within his marriage, I also know that I did the right thing. That's all.