It sounds like the tooling was just being used as an excuse, that they'd decided to fire you regardless for reasons that they wouldn't want to articulate because they'd be grounds for legal action. Just guessing, of course, but don't believe ~everything~ anything you've been told. I believe you've already made good choices in this: take a deep breath and move on, having "dodged a bullet" as others have commented. Good luck with your next gig.