Josh Gordon -- Yes I Boozed ... But I'm Not An Alcoholic

Cleveland Browns superstar Josh Gordon admits he chugged 4 drinks on a private jet to Vegas after the team's final loss this season ... but insists he's NOT an alcoholic.

Gordon just spilled his guts in an open letter to several high profile media members including Charles Barkley, Cris Carter and Stephen A. Smith -- blasting them for taking him to task over his reported substance abuse.

In the letter, posted on The Cauldron, Gordon is adamant he's not an alcoholic or a pothead ... but admits he's been making bad decisions over the past few years.

Gordon says he hasn't smoked weed in years -- and when he tested positive for the green stuff during an NFL drug test, it was due to "inadvertently inhaling second-hand marijuana smoke last offseason."

"Truth is, I have not smoked marijuana since before I was drafted by the Browns in 2012  -- and there are years worth of drug tests to prove it."

As for testing positive for alcohol earlier this month after an NFL-imposed ban from booze (following his DWI) ... Gordon says he imbibed with teammates on a private jet to Vegas on January 2.

"Just days after our season ended earlier than we all had hoped  -- and yes, my actions during the prior offseason definitely contributed to our failure to make the playoffs; it killed me seeing our guys fight so hard when I wasn’t out there with them — I boarded a private flight to Las Vegas with several teammates. During the flight, I had two beers and two drinks."

Gordon says, "It was the first time I had consumed so much as a drop of alcohol since July 4, 2014, the day of the DWI."

Gordon admits "I failed myself" -- but concludes with a message to his celebrity critics: