Celine - I think this last post of yours is much closer to the truth.
Also clears up some confusion and misunderstanding I had regarding your plans for discussing adoption with your son, so thank you for that.
What I see a little bit of is the challenge in separating out your own feelings regarding his birth parents and wanting to protect him from all of that. I understand that one! I don't always succeed in doing this myself. I try to remember that my feelings regarding their bparents are my own and there are just things that I owe them as their mom. Things I shouldn't have to tell them because of someone else's mistakes or wrongdoing, but ah...that's motherhood, no? Just a bit more difficult I think.
I just hope you can find a way out of the negativity issues surrounding it all and focus on the positive aspects too. I'm sure you do this already, but maybe try to remember that his adoption and joining your family should also be included in that positive line of thinking. It doesn't have to be full of the details and hard things right now. There is time for that.
Facing your fears is a good thing too and I wish you the best on continuing to do that.