There is space between flipping out and being mute for collaboration.
I actually don't think you have done anything controlling (YET) with respect to this Saturday night, but I just don't know where you are going to end up with this, the direction of your thinking is what I am talking about. I agree that this one Saturday night isn't worth worrying about. Stuff happens, it is a new job, etc...
But there is something in what you right that sounds to me to be sort of an implicit martyring yourself silently, yet resentfully, in trying to figure out how to fix things yourself so that he is free to work as he chooses and it seems to be creating some bitterness and fear in you.
You are doing something different -- not flipping out, simply being mute instead. But, I'm not sure how deep this difference is. Neither is a form of effective communication or collaboration.
Thus my suggestion that you take a different approach to trying something different: "SO, great news. Let's talk next week to figure out how we'll make this work with the kids."
In a nutshell, treat him as an equal partner who also bears responsibility for finding childcare, babysitters, and other alternative childcare. Both of you will need to be flexible and open to occassionally being that source of alternative childcare if this is to work.
