Sometimes the right solution is to walk away, regardless if it destroys something. Maybe the businessman was unwilling to renegotiate or was a prick. I have no obligation to stick with a job that isn't doing it for me. Maybe it's the businessman's fault for not finding a replacement?
As an aside, you seem awfully defensive of the businessman despite not having the full story.
I've been in this situation before, and bailed before any real work got done. That's when you need to realize these things, not after you get funding.