Just prove it to your new boss.

Not trying to unrealistic here, but what if he knew he was going to lose his job and tried to convince the board into letting you fill his position?

plot twist: he was messing around with you because he knew he was gonna be fired.

This might sound wierd, but to me OP sounds at fault because it's not like OP lost his job or got downgraded. I understand how that is a disappointment because he must have worked hard for a promotion, but imagine how stressed the boss now feels. He just lost his job. He had bills to pay, too. I know it's not the main idea of the post but it's just how I see it, like how we always look for how we are affected by someone else's problem

Just cause you got fired doesn't mean you won't get promoted

I think it's just on the corner.wait for another chance.

FYBL

That really sucks; pretty much the exact same thing happened to my wife. I feel ya, OP.

That's harsh.

Something similar but even more bizarre happened to me, TWICE! I received a job offer from a client; accepted the first one, went on vacation before giving notice at my current job; guy who offered me the job was fired while I was away, HIS boss rescinded the offer. Second time, different client, received an offer, before I was even able to accept it, guy who offered me the job was fired, and that was that. So, I feel for you. That really DOES suck. Hope something even better comes along for you. Good luck!