Dear CB.
What a fathead.
Attorneys make big bucks. I say call him TODAY. He may have some action he thinks of that could be legally important for you, such as a warning letter to xN to not leave without responding to xyz.
Or not, but on the chance there might be a legal ramification that could work to your advantage that your lawyer would need more than a few hours to prepare...I'd go ahead and call him now. (You never know, he may have planned to leave without a word to you, but emailed you on the advice of HIS attorney. Stay alert. Don't trust. Call your lawyer, imnno...)
Seriously. It's not a crime to call these high-paid folks on weekends in an urgent scenario. I think your stbxN's actions do demand urgent legal awareness. There may be nothing needs doing, but in case it's an opportunity, I wouldn't let the day-of-the-week custom get in the way.
love to you,
Hops