Ok I am just going to say it Karma. THIS IS BS! When it comes to the kids there should not be a schedule.
Contact your attorney first and get the facts. After you speak to him call your W again and try and have a civil discussion about rearranging the schedule to fit your work schedule.
If she becomes angry and refuses then call the attorney back and have him send the pre-typed letter.
When W calls to complain in a calm loving voice explain to her why you took the action that you did.
Since she is unable to conduct herself in a civilized matter she gave you little choice.
The robbed that smiles, steals something from the thief.