a "clean break"?
what the heck does that mean?
Personally, I've seen too many PBP adventures stopped by the DM.
I think the novel thing would be to continue once Mark gets the time freed up in his schedule.
Mark - you've already done the part of the adventure that takes the longest - the setup and creation part.
Keeping it going should only take an hour or so a week, I would guesstimate.
So it's totally up to you, of course, but I didn't see any signs of the adventure needing to be dropped before you had your time-squeeze...