So SM - your DS pleaded with you in front of his teacher not to tell daddy and then thats exactly what you did!
Why on earth did you betray your son by telling him?
Couldn't you have made something up???
You need to protect your son from your abusive husband, I just can't for one moment understand why you told him.
Why can't you just tell your DH every day that DS has had a fantastic day at school - why are you perpetuating his misery.
You really do need to think about how all of this looks to your DS - he really is going to be damaged for life by all of this and at the moment I think he will hold you as responsible as your DH
I'm sorry this is probably not what you need to hear right now but I am so so angry on your DS's behalf.
I am now beyond being concerned about your DH's treatment of your DS, to being extremely concerned that you are failing to protect him and actually seem to be putting him in the firing line!