Well, mb, it depends onthe strategy you want to use. So showing caring behavior during NC sends mixed signals...
That's the other thing, in addition to risking a fight, it compromises your boundaries.
If you want to press him to end his affair, you have to show him you won't tolerate it... being NICE doens't send a message to him that you are being HURT and want him to STOP, it tells him you are ok with him with another woman and to keep it up...
All of the info above you can get to him through third parties.. it doesn't HAVE to come from you, and I wouldn't even recommend it...