Suffer me that I may speak; or, suffer me, and I also will speak. There is an emphasis on the "I" ( אנכי). Job implies that his opponents are not allowing him his fair share of the argument, which is an accusation that can scarcely be justified.
Since the dialogue opened, Job's speeches have occupied eleven chapters, those of his "comforters" seven only. But a controversialist who has much to say is apt to think that sufficient time is not allowed him.
And after that I have spoken, mock on. Job does not hope to convince, or silence, or shame the other interlocutors. When he has said his say, all that he expects is mockery and derision.