9:40 PM PT -- Cardi has declared full-on war, sending a message to Nicki, "I've let a lot of s*** slide! I let you sneak diss me, I let you lie on me ...But when you mention my child, you choose to like comments about me as a mother, make comments about my abilities to take care of my daughter is when all bets are f***in off!!"

Cardi goes on ... "I've worked hard and come too far to let anybody f*** with my success!!!! Bitches talk about all that s**** in they raps but in real life are p***y!!"

9:15 PM PT -- People connected to Cardi tell us, when Cardi approached the table she was not looking for a fight ... they say she wanted "to address the lies Nicki was spreading." They believe security had a plan if Cardi came anywhere near, and one of them elbowed her in her face (check out the lump). They say at that point it was on.