NO emotional responses. Ask a good friend (or us) to vet them before you send them.
Anything you send should be strictly the facts and should "sound" friendly even if you want to bash him.
Don't say anything about how his actions have caused this - judge won't care.
Just say: Yes, I am aware of X problem with W kid and we are doing Y and Z to remedy it.
No, I am not badmouthing you to the boys, people often have problems with their teens, I suggest you go to family counseling with them.
I have the same kind of BS with my ex, except our kids are in their 20's. He gets super anxious when they have a problems, and wants me to get on board with his (usually overbearing) response. I try to keep my responses as emotionless as possible. (btw, my youngest currently refuses to speak to his father and feels completely unsupported and misunderstood by his father. )
Your kids have the extra burdens of being anxious about YOUR health, and of having to deal with the OW as a stepmom (thankfully my ex is married to a woman he met a year after our separation, not one of his OW).
You could kindly suggest that your older boys might respond best to having some private time alone with Ex, and perhaps he could make some time for that? That would be good to have documented if he replies that they should suck it up and be with the new "family".
Maybe something like : "I have never badmouthed you to the boys. I am sorry that you are having problems connecting with them right now. I too would like to see this issue resolved as I think boys need their father. Since you are the adult here, I think it would be best if you could be the bigger man and persist in contacting them. I think both of them would appreciate some one-on-one time alone with you - perhaps if you offered that they would respond? If not, perhaps you could convince them to join you in some counseling sessions."
That makes you sound like you're trying to solve the problem, and shows him to be the narcissist if he declines these very sensible measures.
