I vote for walking away. They're not hurting from this incident, you are. Don't rent them space in your head for free.

And whatever you do, DON'T disclose your bipolar to the next employer. I agree with Christina, I think you were set up to fail because of your illness. The Americans with Disabilities Act is toothless, employers are technically not allowed to discriminate against us, but there are a million and one OTHER ways for them to get rid of us. I've been burned too, so I know.

This will definitely need to be worked out in therapy, but for now, just walk away with your head held high. You've done nothing wrong other than to trust the wrong people with sensitive information. It happens to a lot of us. Best wishes.