I am just rolling my eyes here...
And, just HOW did she get the information about the upcoming vacation plans??? People ususally get what they ask for!
As I have said on every single one of these threads, inlaw issues are, in reality, MARRIAGE issues.
If my husband let this go further than the next 24 hours without taking care of the situation with HIS mother, then I would have serious problems about his respect (or lack there-of) for me as his wife, and our kids as well.
Your kids have a RIGHT to a normal happy family vacation with their parents.
She is a toxic person, and I would simply refuse to let her control my plans and spread her poison. If she decided to start with the whining and the cold shoulder, she would quickly find out that I would simply refuse to be in her presence.
The answer here is obvious.
Speak to your husband.
Tell him that you want and NEED this vacation with him, but that you will simply refuse to travel if she is involved in any way.
Yes, you are right when you ask how to deal with 'your' issues.
It is not how to deal with your issues with your MIL...
It is how are you going to deal with these issues with your DH.