Does he know he's not my baby's father?

I have a son, he's 8, and his dad is not my son's bio father. <br><br>My son's actual father died not very long after my son was born. Before he died, he wrote me a letter and asked me that never tell my son about him, and raise a nice guy as his father. He even said he forgives us but he knows his family will never. I wanted to tell my son the truth before he died but he begged me and I couldn't do it. <br><br>His family were very mean and nasty and cut contact after his death. <br><br>My son's dad (the one who raised him) is and has always been great. He's ignored the nasty comments from family and friends, and even spent many nights awake and distraught because of the comments and the fact he's raising a child that's not his and even considered leaving. <br><br>He's never told my son he's not his dad. He's always said he is, he always and forever ignored any negative comments and loved my son. He even told his friends that ignored us that they could fuck off and he doesn't want anything to do with them. <br><br>So my question is, and I know I should ask him not strangers online, but he's never said anything about it before and I don't want to ruin our relationship, but, does he know that my son isn't actually his? And if so, why would he continue? And if not, and he thinks he is, why does he sometimes look at him differently? Like, he looks extremely happy when he looks at him, and I think, actually, he probably does think he's his. <br><br>I don't know. I'm just confused.