I am sorry to hear that school is so painful for him right now. I know that homeschooling is not an option for everyone, (and as a public school educator, I am typically reluctant to simply exit the system--but then again, as a homeschool parent, I guess I do that every day!) but at this point, I wonder whether you have anything to lose by giving him a break from this environment. It sounds like the only educational experiences he's had recently that have been positive have been the CTD and CTY classes that attending brick-and-mortar school is preventing him from accessing. He is not receiving anything at school that you might feel like you wouldn't be able to get back if you pulled him out now. And he appears to be miserable.

At the least, this might be one way to communicate to him that you see and acknowledge his suffering at school, even if the school has not responded to your efforts to improve things. You don't have to cover every subject every year as a homeschooler, so if you just sign him up for a couple of CTD or CTY courses, that wouldn't be an unreasonable way to cover the next few months of school, while giving him some space to breathe, and perhaps regain some of his love for learning. And life.
...pronounced like the long vowel and first letter of the alphabet...