So you were building a service that competes with a service Facebook was working on, they offered to buy you out, you declined, and you're angry about this? I'm sorry, but that's absurd. Most companies would not have even thought about steamrolling you, forget about offering a check. Did you expect them to just decide not to pursue their App Store offering because ol' Dalton Caldwell wouldn't like it? That's fucking ridiculous.
It sucks that you were naïve about this, but that's hardly Facebook's fault.