Hi Op , I think we tried to be honest with our kids too and in hindsight probably said too much as we were worried that one of our children had overheard things .
Apart from initially they haven't really acknowledged or wanted to discuss the separation . I am also not sure they have even told their friends , although I have flagged it up to their school .
I think for teenagers generally , but can't comment re the ND aspect , they are at a " selfish " stage in their lives and are dealing with hormones and changes to their bodies . They aren't really interested in their parents lives as a whole .
As your children are ND , I am not sure if they are getting any support . If they have a social worker or therapist / professional assigned to them and if so , are you able to get any input from them about how they would advise that you address it with them ? If not , is this something that you can speak to their school( s) about and seek guidance / support there by way of guidance / counselling ?
Schools will be very experienced in this as sadly a number of relationships do break down .
Take care of yourself . This is a tough time and it is also difficult when children are in the mix and we are trying to do what is best for them too .
If you Google you may find some useful articles . I have found some of the Pyschology journals a good source of advice too .