Insane scene in a Halloween MMA match ... a fighter snapped her forearm in half -- BUT TRIED TO CONTINUE THE MATCH ANYWAY!!!
It all went down Saturday in Sao Paulo, Brazil at SFT MMA's Standout Fighting Tournament 22 ... when Sidy Rocha was taking on Karine Silva.
At some point during the first round ... the two fighters got on the ground -- and Silva appeared to lock Rocha's arm in a submission hold.
That's when Rocha's arm broke ... and, WARNING: THE VIDEO OF THE SCENE IS GRAPHIC!
But, to everyone's bewilderment .