I have to admit, it took me three days to read last your post. But I wanted you to know I read it, and though I might be a little fuzzy in my response, it is not because of a lack of trying or caring.
I understand a lot of what Tsol wrote about in her last post... the tests and the never ending "Why? How? What happened?" in your head. But the thing I agree with most is that it sounds like your boyfriend, Brianna, is talking down to you. I couldn't quite put my finger on it, but when tsol said it, it totally clicked. I understand how hurt he is, but I do not understand his goal in all of this... I'm assuming communication was pretty poor before the affair, but now he feels like it is great time to be bring up EVERYTHING that has bothered him in the past couple of years. I also feel like he has a slightly idealized fantasy of what a relationship should be like at the three year mark. Not to mention, I feel he has a pretty skewed vision of the world because his pride gets in the way (come on, it was more of a sacrifice for him to take money and stay with you than to for you to cover him? I understand it being a sacrifice on his part, but still pretty egotistical to see himself as making MORE of a sacrifice than you -- like he refuses to see what positive things you do in the relationship). I feel like he is always trying to one up you, trying to separate himself from you.
I guess my concern is that he is going to be fighting against any work that you would put into saving the relationship. Granted, I think some of that is to be expected. Like Tsol said, there's going to be a lot of testing limits, a lot of "Do you really love me?"s. But I think he has to be willing to communicate with you more, in a more supportive "I want to be with you" way. This could take a lot of time for him to reach that point, but I think you need to find out if he WANTS to reach that point. Or if this is something that is always going to be hanging over your heads, something he feels perfectly justified in bringing up to hurt you. Over time, those tests should get fewer and farther in between. He should be willing to help shoulder the burden of healing the pain, without reminding you that he is doing it every time you struggle a little.
I'm a little confused by the whole changing thing. To me, it seems like half the time he's saying "You changed in the last year" and the other half of the time he's says "You changed right after we started dating." Maybe you need to explain this a little more, or maybe just more concisely so I can see it all on the same page
And one last thing... I'm kind of curious about the whole legal issues with your son... Do you think you can explain this also? I guess I'm just confused about why he feels like he doesn't want any sort of legal connections to him. Has he always felt this way or is that only since everything happened?
I'm sorry if this wasn't any help. Like I said, I'm a little jumbled from reading it disjointedly. I'm very sorry for everything that you've been going through.

Take care