OP I've just read it all too. I'm so happy you got out and another one who is right behind you.
I may have missed this but I haven't seen it said so wanted to add.
Your DS sounds like a really lovely boy. He sounds kind, sensible, empathic, socially smart and very importantly too he's able to be open and honest with you about how he's feeling.
Two things stand out for me from that.
First, he's grown up with an incredibly abusive father, yet he's not really anything like him. While the homeschooling and working from home ideas no doubt were about co trolling you, what that may have done was shelter him from a lot of the negative impact of the extreme stress caused by his father. You have been a soothing influence, steady, stable and loving. While obviously his father has impacted him, he's also been able to cling to the rock of safety that you provided throughout even the worst storms. He's not had to go through things like bullying at school, or minor mishaps with friends, stressful class situations of teachers. While in ordinary circumstances they may be fine, in your DS it would have been additional stress. Staying with you has meant he's had time with very limited stress. This is a great thing for his social, emotional and quite possibly neurological development in the circumstances.
Second is that while his father has shown him what it is to shut emotions down, you have shown him what it is to have a voice and he heard. He told you he wanted to leave and you saved him.
Thirdly, all the goodness that oozes out of that little boy of yours is an absolute direct reflection of what you filled him up with. You are an incredible mother. If you ever, ever doubt it, look at him and how he is: he couldn't be so lovely if your ex had spent all that time with him instead of you. Your ex's behaviour was a negative parent in force (even in the good times, because he was setting DS up to mistrust). You overrode most, if not all of that. You have a natural strength beyond what you've realised.