What made you think it was appropriate to discuss your (admittedly unfounded) assumptions about someone with his boss? I’m baffled that you found this OK, and even more disheartened that your impulse was to diagnose someone. Diagnoses are inherently subjective, and bipolar disorder is less a medical condition than it is a framework for understanding deviant behaviour. This is such a betrayal, and while the boss was discriminatory, and a peer you should have realized the implications of what you were doing.