Last weekend my stbx left D's bike helmet at his place. We needed it, I asked him about it. His response? No apology, just "maybe you can borrow from a neighbor"?
In other words, don't over think it. This is not a life or death sitch. These things happen-- they are the result of HER leaving and it's impossible to never make an honest mistake. Don't bend over backwards to solve it for HER. (If your son asks, that is different).
Definitely don't make a joke of it as that sounds condescending. But just be honest - it was an honest mistake, these things happen, maybe we can discuss a system to make the packing process go more smoothly next time. See you at pick up on Friday!
Easy breezy, not defensive and not doormat. Good luck.
