“looking to see what I missed, what I didn’t give this child”
Again, it’s not about giving or permissiveness, or even approving of what he’s doing. It’s about accepting him for who he is and loving him for who he is, not what he might have been. Not that I’m saying you don’t–I don’t know you so I obviously can’t judge or even comment on that–I’m just giving some of my experiences. Giving a kid things isn’t loving him, nor is being overly permissive necessarily.
You said that he was the first child and got the most love, and then you said that there’s something that you know of which may be making him angry. It’s quite possible that that situation is making him forget everything in the past. You need to love him now as he is. You can obviously try and steer him in the right direction, after all that’s what parents are for, but love him for who he is now.
Again, I don’t know you, your kid, or your family, so please don’t take what I say the wrong way. I’m just speaking from what I know.
“The other issues are situational, and are not something we can change.”
Whatever it is, if he won’t agree to see a therapist then perhaps you should. The therapist will be able to A) better equip you to handle the stress you’re currently obviously experiencing, and B) possibly help you bring your son back by teaching you what to say, do, etc. I’m not an expert, I just have a little experience.