01/17/2007 AT 09:00 AM EST
T.R. Knight says hearing Isaiah Washington call him a "faggot" on the set of Grey's Anatomy
gave him the courage to come out of the closet – and that he's speechless that Washington on Monday denied using the word
In an interview with Ellen DeGeneres set to air Wednesday, Knight
says something changed inside him when he overheard an argument in October
between Washington and Grey's
co-star Patrick Dempsey during which Washington used the slur.
"It's an awesome word, isn't it?" the 33-year-old actor tells DeGeneres sarcastically. "I've never been called that to my face. So I think when that happened, something shifted, and it became bigger than myself."
Shortly after the dustup, Knight confirmed exclusively
to PEOPLE that he is gay – the kind of announcement he says isn't his style, but that he felt was necessary.
"I was under no delusions," he says. "My friends on the set knew. We talked about it. Publicly it's not my thing to call up PEOPLE magazine and be like, 'Hey, you want to know something about me?' ... I could've just let it slide and not said anything, but it became important. It became important to make the statement."
In the Golden Globe press room on Monday night, Washington denied using the slur. "No, I did not call T.R. a faggot," he told Access Hollywood.
"Never happened, never happened."
That statement drew a sharp rebuke from another Grey's
Katherine Heigl, who said Washington "needs to just not speak in public." And Knight tells DeGeneres he doesn't know what to make of the denial.
"I don't know what to say, really, about that," he says.
Knight also thanks DeGeneres for having the courage to come out as a lesbian 10 years ago. "It just made all the difference in the world," he says.