Reaching out with great sympathy for you and your family. I know from personal experience that watching your child struggle is so very hard. But you seem to be proactive and caring parents with the right goals for your son (being happy)... and that's going to make a world of difference.
I'm not sure I have enough data to give you specific advice, but you may consider the following:
1. A "come to Jesus" meeting with the school (after all, the unreported physical assault, lack of trust and emotional support, etc. are bigger issues than just an academic problem).
2. It may be time to start looking at school options, again. Since you've already taken that ride once, I'd suggest looking further outside the box this time.
3. You might look for a therapist for your son who specializes in gifted issues. This person can not only help your child process difficult feelings, but can also assess and provide an outside point of view that you can use in advocating with the school.
