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T-Pain stopped appearing on DJ Khaled albums all the way back in 2013 -- he's calling it an act of betrayal, after he propelled Mr. "We The Best" to platinum status!!!

On the latest episode of "Club Shay Shay", Shannon Sharpe simply asked T-Pain what's the one lesson he learned as he approaches his debut album's 20th anniversary ... a0nd T-Pain immediately brought up DJ Khaled.

T-Pain says the most invaluable lesson he learned was that nobody is your brother -- especially those who always tell you they are!!!

It's crazy to hear their partnership corrode like this ... T-Pain actually helped Khaled earn his FIRST-EVER Platinum plaque back in 2008 through their "I'm So Hood" anthem, but the chili peppers are now under the bridge. Play video content

We just caught Khale

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