Actor and comedian Brad Garrett sat down with ET's Brooke Anderson to open up about his alcohol-addled past and what made him face his demons head on.

"I was what they call a high-functioning alcoholic," Garrett told ET. "I hid it really well."

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Garrett, 55, said that he stayed in denial about his drinking for a while in part because he "was really never a day drinker." Fortunately, he faced the music just in time for his career to really explode.

"It was just a realization that I probably wasn't going to make it," Garrett said of why he decided to change. "I would hit a fifth a day sometimes, and that's a lot ... Raymond had just really started to take off. It was after year one."

Garrett famously played Ray Romano's brother on the CBS sitcom Everybody Loves Raymond from 1996-2005.

As with many comedians, Garrett had to find a way to cope with pain. In his book, When the Balls Drop, he reveals that he used comedy as a defense mechanism for everything from bullying to his 2007 divorce from Jill Diven.

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"I'm with someone now who's a little young," Garrett said, referring to his 31-year-old girlfriend Isabella Quella. "We had an AMBER Alert the other night when we went to the movies."

Garrett isn't the only one poking fun at the age gap between the two. Legendary comedian Don Rickles teased them during a run-in at a restaurant two weeks ago.

"Rickles walks up to the table and he looks at her and he looks at me and he goes, '12? 13 maybe, Brad?'" Garrett said. "And then he looks at her and goes, 'You being kidnapped, honey? Blink if you're being kidnapped.' I immediately put her in a timeout."