Jermaine Dupri -- My Ex-Friend Is an Ungrateful Bastard ... Who Ruined My Hummer!

Jermaine Dupri lavished his friend with a free place to live, a free car, free studio time and several other gifts ... and the guy repaid him by trashing his hummer and then having the audacity to sue him.

Dupri says Taddrick Mingo is a leach who did nothing but take, take take:

-- free recording studio time
-- 4 years free rent in a 2 bedroom condo
-- use of Dupri's Hummer
-- free computer
-- referrals so Mingo could get studio work

Jermaine says Mingo then turned around and sued him ... claiming he worked as Dupri's assistant but never got paid.

So now Dupri has fired back with his own lawsuit, claiming Mingo was NEVER his assistant. And Jermaine wants money for the financial beating he took when he sold the whip at a loss.