That really is awesome, Star! He showed a great deal of maturity to handle it the way he did and I'm really proud of him. And I think you gave him the groundwork to come to his own conclusions in his own time.
It's a painful thing but kind of liberating in a way. My ex was there when the kids were growing up but it was awful for them! He treated the two of them completely different - could care less about our son and didn't bother to hide it, while he sort of cultivated our daughter. He "used" both of them but in different ways. My son always knew his "father" was a schmuck but he never talked about it - I know that the way he was treated made him feel very bad. My daughter always felt obligated to feel sorry for him, tried to understand him, to stand up for him, until he "used" her one time too many, and now both kids are on the same page. My son was in his mid-twenties before he finally felt free enough to talk about it, and it's been very liberating for him! He always had it in the back of his mind that he was somehow to blame, that he just wasn't good enough, that it must have been his fault. Now they know better! He still has a great deal of anger, and it sometimes comes out at the wrong target, but he's a lot better. He's finally confident in himself enough to get MAD about it, and it was a real turning point for him. He seems so relieved that it's all out in the open now, and he knows that it wasn't him! His father is just a donkey-butt!
I know this must have all been very painful for Dude, but in the long run it cleared the air and now he's looking at it from adult point of view at a very young age. You should be very proud of him.