While I do not think OP owed any reply email, and I almost always agree with still in va's posts, I will in this case offer the slightly dissenting view that some people do benefit from being called on, or told the collateral and direct results of their actions.
While many, and quite likely the previous child carer in this case, will not "see the light" and they either realize the impact of their actions and don't care, or will never "get" that the world doesn't stop for them as they wish - some would take a wake up call and use it to open their eyes.
I know I have personally benefitted from feedback which opened my eyes to impacts of my own actions, which I then immediately set about revising. Nothing on the order of the OP's previous babysitter's behavior, and I don't think feedback is "owed" here. But just as "common sense" isn't all that common to all, some folks *can* have a lightbulb moment when hearing something like "your prior actions greatly inconvenienced me, and caused a sudden change for DD without time to plan. DD is happy with current arrangements, your previous lack of reliability would prevent me from ever hiring you again, and - as DD is now doing well - meeting with you for closure is not desirable for us."