The man behind the suit is ex-Michigan State football player Jermaine Edmondson -- who says Draymond's posse attacked him and his GF at an East Lansing bar on July 10, 2016.

Edmonson says he confronted Green the next night -- and Draymond punched him in the face. A cop who witnessed the attack arrested the Warriors star for assault.

But Edmondson says his life has been hell since the incident -- and things got so bad at MSU (where Draymond went to school) that he quit the team and left the university for a while.

Edmondson says he's still haunted by the attacks -- and feels his name has been turned into a joke thanks to Green.

"I think about what happened with Draymond every day. I still feel his hand on my jaw."

Now, he and his GF have lawyered up with Lisa Bloom -- who's repped stars like Blac Chyna and Kathy Griffin -- and have sued Green for assault and battery.

As for Green, he cut a sweet deal in the criminal case -- he agreed to stay out of trouble for a year and the charge was reduced from a misdemeanor to a civil infraction. The year ended on July 22 so he's basically in the clear with prosecutors.

11:22 AM PT -- Draymond's camp issued a statement saying, "This lawsuit relates to an incident that occurred in East Lansing, Michigan over a year ago, for which Draymond paid a noise violation fine."