I've been in a similar situation and all I can say is I feel you. I've become very distrustful and suspicious of people in this industry, especially the fast-talking "we're changing the world" kind.
Ultimately, if people want to renege, they will renege. Unless you have a ton of money and energy to throw at lawsuits, it's better to structure your deals in a way that clips your potential downside (e.g. work on a retainer basis, don't accept stocks in lieu of cash etc).
Ultimately, if people want to renege, they will renege. Unless you have a ton of money and energy to throw at lawsuits, it's better to structure your deals in a way that clips your potential downside (e.g. work on a retainer basis, don't accept stocks in lieu of cash etc).