If you opt out, is your dh still going? If you are *both* going to opt out and reschedule for sometime after the eval next week, I think that would be fine. If your dh is still going to want to go tomorrow, I'd go. As the parent who's taking charge of the attempt to learn what's going on with your ds, you need to hear straight from the teacher herself what her perception is of what's going on at school with your ds - whether or not she's right or mistaken, you need to know what her perception is. You also need to be there to speak up for your ds. I think it's important to let the teacher know what happened the night before the quiz he had such difficulty with. It also sounds like you see something that may be going on with your ds that the teacher and your dh aren't seeing - so you need to be there to be his voice for those concerns. One other thought - I'm not sure what type of professional you are seeing for the dysgraphia eval, but it might help for you to go so you can ask some specific questions of the teacher that would be useful for the evaluator to know about your ds if there are any you might still have and haven't already had an opportunity to ask.
I know how hard it is not to be burned out when you're the parent who is responsible for all of this type of advocacy, and I also know how hard it is to worry that you'll blow up in a meeting - I used to get so mad at our ds' school staff at times! But it's worth it to do your best to go ahead and go, as much as you don't want to, and to try your best to hold the frustration in and speak up for your ds. What I did before meetings like this that I worried might become confrontational was to think through every possible thing I could come up with that the teacher (or whoever) might try to say about my ds or his work etc - and come up with a to-the-point reply that countered their statement. I'd write those brief replies down and rehearse them if I had time, then when I was in the meeting I would just do my best to stick to them and not let my emotion show. It's MUCH harder to actually do than it sounds like, I soooo know that - but just approaching it that way ahead of time - over-prepping, having notes, having planned replies - helped me to be able to stay more consciously focused at the meetings, helped somewhat with keeping meetings on track, and definitely helped me get the important info out there at the meetings that I felt needed to be said. I also never really looked at the notes in the meetings (except a glance at the end to be sure we'd covered everything I wanted to cover)... just going through it ahead of time was really what worked to help keep me calm
Hang in there!
polarbear