My two cents on this quote would be to interpret Hamlet's words as part of his growing acceptance of his own plan to kill his uncle. Through much of the play, Hamlet is fighting against this course of action. His father's ghost makes a clear mandate on him, but Hamlet does not want to kill his mother's husband, even if he is a murderer. Of course, Hamlet also does not want to become a killer. So he struggles against this course of action. Eventually though he comes to feel that he must kill his uncle. This quote finds Hamlet justifying his future actions, saying that there is no way around his fate, despite any attempts he would make to avoid it.