Sorry for the less than helpful suggestion. I live in NJ where divorced parents ALWAYS or (virtually always) are obligated to pay for the kids' education--sometimes even post-graduate education (which I don't necessarily agree with--not when non-divorced parents don't have the same obligation).
I think a "Plan B" is a very good idea, and I think to make nice with someone so he doesn't threaten you is kind of creepy, to say the least.
You might want to talk to a lawyer about whether his verbal promise to his daughter, which she relied upon in choosing the school, might not be enforceable. Legally, gifts can sometimes be enforced when the recipient changes position in reliance on the promised gift.