I would continue to pursue the job opportunity you were, and if they seem very interested in you, let them know the deadline of May 1st as that could expedite an offer. Make sure you get the offer in writing!
As for your supervisor, what an unprofessional piece of work she is. I wouldn't take anything she says at face value. What's the saying, trust, but verify? I would maintain the contact you have with the superintendent and bring up this latest incident in your next conversation if there's an opportunity. He is aware of what is going on with your supervisor, and I hope he is investigating it for himself. You've gotten the ball rolling on that situation, now keep doing what you are so good at: acting with integrity and with the kids' best interests at heart.
I'm sorry for everything life has been throwing at you, I've followed your story for a while and hope that things will start falling into place for you. You handle everything with grace, and you deserve some good things coming your way. We're rooting for you!