head ache from below

We have developed a crack in the ceiling of our living room in our 70+ year old home.
The crack seems to have gotten large in the past few week
Now the head ache for a man who is all thumbs to try and fix it. This view is from our
our living room looking up. If I manage to fix this crack, remove all the "popcorn" ceiling and repaint without destroying the living room or having my wife kill me out of frustration, I'll post a new photo of the finished work.