Macbeth says, "I am in blood Stepped in so far that should I wade no more. Returning were as tedious as go o'er." What does he mean?

Macbeth has gone so far into killing that it would be easier for him to surrender himself to the darkness until he can't go back to the way he used to be. He is literally and metaphorically steeped in blood, he cannot return to his former self.

Macbeth has stepped in such a killing spree, that he says it as " I am in blood", then says " stepped in so far" means involved in such a way, then " should i wade no more" means metaphorically he has stepped at the middle of a pool of blood, if he do not move forward and decides to come back to home bank it will be similar difficult to move forward and reach to far bank.

What a selectively understood line. Macbeth is saying that I am so accustomed now to killing that it would be more difficult to stop and become the man I was than it was to become a killer in the first place. Frying an egg is easy, turning a fried egg back into an embryo is almost impossible. This quote rings truest for ex-military persons like me. Wading in that type of lifestyle is something we just can't let go. To relate the first world war, from which this became such a prolific quote among military; " as tedious as going o'er". This mean "going over" and I shouldn't have to explain too much more about that. However, unlike going over the trenches which didn't exist in Shakespeare's time, his trench was the metaphoric innocent divide a person crosses before they become a killer.

there is nothing Macbeth can do to undo the trechery and murder he has already caused. He can never go back. The only way is forward what difference another murder?