So, where are you working today?
Two questions I would ask about your being "passed over" are these --
1. Were you the most QUALIFIED person for the job? If not, that's something to work on. Learn more about supervision (it's not just a title) and see if you can display some LEADERSHIP in the position you now occupy. Leadership does not require title, but it usually pays off in the end.
2. Have you talked to anyone in Human Resources? Your COO may or may not be a thoughtful, skillful manager him/herself. Someone in HR will know if the "oversight" was lawful or not. If your facility did not do a thorough job of weighing all candidates (please tell me that you did actually APPLY for the job, and were not expecting them to hand it to you!!??!!) then you may have an opportunity to settle your concerns by pointing out to the management that your rights have been violated.
Don't be discouraged. You may have learned an important set of life lessons here. And, you may want to take your talents elsewhere!
--p