I would put money on their class mates knowing and not wanting to get involved - don't expect support from there. Their classmates' embarrassment will make them just ignore it all.
I think your eldest son's condemnation of his mother would have more clout if you are willing to give him that information. My kids were 15, 13 11 and 8 when they found out. I don't know if it is right to lay that burdern on their shoulders; I was just so shocked that I didn't think about keeping my voice down, I say now with great shame. However it did resolve things.
Saffie me 46 H 46 M in 1986 D20,D18,S16,D13 H's A 01/05 to 07/06 H recommitted to M 07/06 renewed vows 09/06 Going from strength to strength