It is clear in your post that you are not ready to have a sit down with him and guess what ... that's ok! First of all, any excuse he has for the A is bullshit. If he continues to blame it on your adult son moving back home or perhaps he has some new shiny excuse that, of course, will be your fault, why waste your time and energy on listening to it?
If he wants to discuss finances, he can do that in an email. That will allow you to read, process and then respond in a non-emotional way. If he wants to discuss divorce, he can also do that through email.
In time you will see that any discussion about "the demise of the marriage" won't really help you. Basically, WS's are selfish entitled cowards. Some here have additional issues (NPD, SA, etc) but that doesn't change their foundation of being selfish, entitled cowards.
A simple "My schedule is really tight so please email me instead". No apologies ~ just the basic truth.