I am sorry that this is a fact of life but...it is. All negotiations in a divorce are hard and everyone gets screwed.
Do they have kids? Will she keep the primary residence? The business may be struggling but in this economy EVERYONE is. So, there is an assumption that when this is over, his business will be back to the way it was before or better.
I don't know how long they were married, but I imagine that she has become accustomed to a certain lifestyle and she wants to keep it. He unfortunately is the one to have to pay.
Does your son still love her and not want the divorce because of that or does he not love her but would stay married to not deal with the aftermath?