This is one of the extremely RARE times when the movie was better than the book. In the movie, things escalate logically, with a little humor to keep it from getting too dark. Even at the end, when both spouses have "lost it," there was an enraged logic to their actions. In the book, things got TOO over-the-top. Filling a bathtub with rancid food, turning the whole house into a booby-trap, it was just not believable.
At times, it digressed into a "women's lib" commentary on how a woman exists just to validate a man. A key plot point is that Jonathon doesn't understand why his wife wants a divorce. In the movie, we can side with Barbara at times, just as we side with Jonathon at other times. In the book, she just comes across as needing some cheese with that whine.
Get the movie, skip the book.