Congratulations! I'd tell your ex-wife the good news, "The school called. D17 may end up valedictorian!" I'd also let her know, "I'm open, if you'd like to tell the kids until after finals, just let me know before Sunday." I would not pressure, guilt, persuade, negotiate, etc. Those tend to backfire spectacularly. If she opts to tell them with you on Sunday, remember you have a hand in how easy or traumatic that experience is.
