Your boss is a dick, so he's making it clear they shouldn't need you. Get that shit out of your head that the sky will fall for these people if you leave. It won't.

It's hard to believe, I know, but they WILL find a replacement and life will go on.

If I'm wrong, your boss should've learned not to work you like a whore.

I can feel the OP's pain man. GTFO. Quit.