A Line Mechanic replacing a Recirculation (Recirc) Fan # 2 contactor on an EMB-145; inadvertently breaks the right tab securing an adjacent connector for the Windshield Heat contactor. Concerned about taking a probable flight cancellation; and with the item previously deferred; he does not notify the Supervisor until after the aircraft had departed.

Narrative

I was changing the recirc fan 2 contactor and removed the adjacent connector of the windshield heat contactor in order to gain access to the upper bolt of the recirc fan contactor. The right tab securing the connector of the windshield heat contactor in place; broke off. I didn't bring it to my Lead's attention as I thoroughly checked it out and it was secure with the remaining connector. I didn't feel good about it so I attempted to file a report; but could not do so since the EMB-145 aircraft was purchased from a previous operator and somehow was not entered into our system. I sent a message to Flight Line and the Supervisor. The item was taken care of last night through a special request; which I greatly appreciate as it would have been on my mind until it had gotten fixed. This event was caused by Human Factors issues. The recirc fan MEL was a priority one; but the Supervisor got it deferred. I; being the enthusiastic individual that I am; asked the Lead if I could continue working on it. I troubleshot it (the problem); to the contactor and to change it would take me into overtime. When I broke the tab I felt bad that the Supervisor had deferred the MEL from a priority one status to a priority two; but I wanted to continue working on it. That right there caused me to do what I never do; taking a probable cancellation when the item was already deferred; was the deciding factor in not reporting it. After the fact; I realized that regardless of the circumstances; you MUST always report discrepancies as safety overrides all other factors AT ALL TIMES. I'm terribly sorry this occurred and it will NEVER EVER occur again. No action was taken as the aircraft was released for service being that the discrepancy was not reported.As I stated; regardless of the circumstances present; whether it be time constraints leading to a cancellation or a delay; a bad feeling produced from making a mistake; or the possibility of being written up; or not wanting to fix the mistake; your first priority as an A & P Mechanic is to constantly be fully aware that safety takes precedence over everything else; which is every Mechanic's utmost responsibility.