Hey, ant, Been following along. While it could be considered good that W is proposing addressing the grades, it comes across to me a little like a Drill Sergeant rattling off orders ("Get down and give me fifty!")
Unless I missed someone suggesting this already, I'd set up a meeting w/wife and the appropriate (or all) teachers. This would provide you, W, and the teachers with some much needed info and perspective.
Don't read the nastygrams. You can probably tell they're nastygrams within the first couple of words. Stop at that point and delete.
Hang in there.
Gardener
"My soul, be satisfied with flowers, With fruit, with weeds even; but gather them In the one garden you may call your own." Cyrano deBergerac