"Yeah real good faith and 50/50...you took them almost two weeks the end of June, you're taking vacation the last week of July, and now this time in August. Doesn't sound like 50/50 to me. And as I always remember and will remind you, you've never been a 50/50 person with me...it's always been more one side than the other, in every situation. And just to let you know, they have back to school registration and Camp Turning Point during this time so they will not be able to go anywhere. You are so selfish and always trying to make yourself look better than me. You've done it for 18 years and you continue to do it. Call it what you want, but I see it for what it is and so do others."
Ok. I would take this approach.
"Wife, you are right. I haven't always been a 50-50 person with you and it has always been more my side than your side. You were always the giver and I was a taker. I am wrong for that and apologize and completely understand why you feel that way and don't blame you. I will make other plans for myself for my time off so that it doesn't interfere with your time with the kids.
That's it. And then I would make other plans. I would suspect that this approach will work much better and she will move in your direction. If not, then do what you said you would do and make other plans.