One boundary that I set was that I would not communicate via text. Being bombarded with texts is extremely invasive, and you have a right to have peace in your life.
I shifted communication to email only, and I created a separate email address to use with just him. It was an absolute sanity saver for me. My anxiety had been skyrocketing with texting. With the email, I called the shots on when I would communicate.
And now, even better than email, communication is through Our Family Wizard.
Also, absolutely YES to sticking to the schedule. You know the phrase about "if you give them an inch, they'll take a mile?" It applies here. The schedule is there for a reason. It should only be deviated from in extreme circumstances.