TMZ broke the story ... Williams filed a lawsuit against Crooks ... claiming she suffered serious injuries and psychological damage when Crooks belted her across the face back in January.

Fortunately, the smack was caught on tape and aired on the VH1 reality show. But earlier this month, Williams decided to abandon her lawsuit ... and filed court docs to end the legal war forever. Sources say there was no settlement -- Jennifer simply decided not to move forward.

A rep for Jennifer tells TMZ she is "already dealing with her difficult divorce and did not feel that it was necessary to continue to pursue civil action."

Nia's lawyer Javier Solano tells TMZ, "We have always maintained that the frivolous lawsuit brought by Jennifer Williams was nothing short of a last-gasp attempt to maintain her dwindling relevance on the 'Basketball Wives.'"