Interviewed on Larry King Live on Monday (the interview was taped on Friday), Washington said he regretted not confronting Dempsey the first time he was late, so he challenged him the second time.
But Dempsey wanted to delay the scene more to wait for Grey's star Ellen Pompeo, who plays Dempsey's love interest, before shooting began.
"I said I don't need Ellen, I can act," Washington told King. "And that was the moment that sent it into a different zone."
According to Washington, Dempsey erupted. "He became unhinged, sprayed spittle in my face," said Washington, in his first television interview about the controversy. "I'm asking him why is he screaming at me. ... He just becomes irate."
That's when Washington said "a lot of things I'm not really proud of."
"I said several bad words," he recalled, quoting himself as telling Dempsey: "There's no way you're going to treat me like the B-word, the P-word or the F-word."
He said that the "F-word" was not meant as an anti-gay slur, but implied "somebody who is being weak." Washington also strongly denied he ever directed the word at gay costar T.R. Knight.
"I am not homophobic – in no way, shape or form," said Washington.
As for Knight claiming the slur was directed at him, Washington said, "That's a lie. He misrepresented himself." Washington suggested Knight did that to advance his career and get more money. "He has been very disappointed in playing the character he has been playing. He told me that," said Washington.
But Washington said he felt badly about repeating the slur backstage at the Golden Globe Awards. "I wish I could take that back," Washington said.
He became emotional at one point in the interview. When King asked if any cast members had written to him, Washington paused and appeared close to tears when he recalled that Sandra Oh had sent him an email.
Washington ultimately attended counseling, but was fired from the hit ABC series.
(King said on the air that Grey's producers, Dempsey and Knight all declined to comment.)