Sure, she is thinking of herself. She acts as if there was never a previous discussion regarding the grip.
The boys will have your undivided attention and time. They will love it. Make it a "guys trip" that will be more about making memories of them being with their dad.........instead of focusing on the fact mom isn't there.
It is not about what you feel should work in your M. It is about doing the work that gets the right results. Do what works!