Arguments about who is controlling, in my experience, never get anybody anywhere. Obviously everyone wants control, he to do it his way, you to do it your way. Leave that stuff out of it, and don't go there even if he does.
I'd be upset in your situation, OP. To try to move on, in a conversation with DH I'd frame it as a matter of communication: you indicated this time is a problem, and he should have communicated to his mom and you that there is a conflict at this visit time, so let's see what we can do to make it work for everyone. And he needs to be sure his mom doesn't take it personally. You can speak to your MIL directly, if you're not sure DH will communicate it as you'd like. You can say you want to have her visit be as great as possible, and in your experience you can't separate what is needed for your work from the pressure of having a guest, even your MIL (whom I am sure you adore). THat way, if she ends up coming anyway, she'll be forewarned and you can refer back to that conversation. Good luck.