WATCH: FBI’s Comey gets defensive as Feinstein grills him over decision to reveal Clinton probe

FBI Director James Comey told lawmakers he agonized over the decision to reveal a renewed investigation of Hillary Clinton's emails, just days before the election -- but he said he would make the same choice again.

Clinton said Tuesday that she believes Comey's revelation ultimately cost her the election, but the FBI director said he was faced with no good options after investigators found additional emails on a private server.

"This is terrible, it makes me mildly nauseous to think we might have had some impact on the election," Comey said.

Comey said the choice to speak was a bad option, but a decision to conceal the probe would have been catastrophic.

"I could see two doors, and they were both actions," Comey said. "One was labeled speak, the other was labeled conceal."

He told lawmakers that the FBI had repeatedly told lawmakers the investigation of Clinton's emails was completed, but he felt they should be notified that the probe had been reactivated.

"(To) not speak about it would require an act of concealment, in my view, so I stared at speak and reveal," he said. "Speak would be really bad -- there's an election in 11 days, lordy that would be really bad -- (but) concealing, in my view, would be catastrophic."

He told Sen. Diane Feinstein (D-CA) that he did not publicly announce the investigation but chose instead to send a letter about it to relevant lawmakers.

"Oh, no -- did you really think?" Feinstein muttered, before cutting herself off.

"I know it's a distinction without a difference in the world of leaks," Comey said.

"Oh God": Sen. Diane Feinstein can be heard...by sarahburris