I came across your question posted on advice from June, regarding the homeschooling, and I was wondering if you had to follow through with that or if Josh got better with the school system. My son began to exibit signs of his ODD at eighteen months old. He is now 13. I homeschooled him from grade one to 5, but put him into school last year. We have journied through storms inbetween and the homeschooling became more of a battle than a learning experience.
If anything, what I have learned through these 13 wild years is that once out of a comfort zone, the anxieties become overwhelming for him and that's why his behaviour gets hightened. It sounds like you get overwhelmed as well. Maybe try making it a date/special trip in order to ease the anxiety for both of you. I have found that this has helped us, even if it's only going for an ice cream after, or even before. Depends on what's more necessary for sanity at the time, hahaha! But it ends up breaking the tension. I thought maybe this might help to try. I know how hard it can be and I wish you the best of luck in your journey together.