That’s not true either. Even if Peter killed the cock before it crowed, that wouldn’t have contradicted Our Lord’s prediction. He said “before the cock crows, you will deny me.” If Peter killed the cock before it crowed, and then immediately began denying Our Lord, then the prophecy would be fulfilled. Killing the cock simply gave Peter an indefinite amount of time in which he could deny the Lord.
If Our Lord had said “The cock will crow once you have denied me three times.” Then Peter kills it before denying Him, only then would the prophecy be unfulfilled.
However, your entire point is moot because none of this ever happened.
I just showed you a point in reality in which God wrote down (in effect) a prediction of the future and it came to pass exactly as He said it would. And yet you still deny it because you claim something else could have happened. Well, yeah, I could have jumped out of a time machine and stopped the crucifixion, but I didn’t. Christ knows that there was a possibility that Peter would have choked the cock before he denied Him, but the fact is Christ knew what would actually take place in reality. And He disclosed it to Peter for his sake and for the sake of showing the world that He has knowledge only God can have.
I think you have a problem with the concept of there being possible futures, and definite futures. God has immediate knowledge of all time because He creates it and exists apart from it. He knows all possibilities and “all that could have been” and still knows all that will be.
The sun will either rise over the earth tomorrow, or it will not. Both scenarios could possibly happen, but only one of them will definitely happen. God knows both possibilities and what will definitely come to pass. So it is with everything else: God knows all that could have been, and all that actually will be. Just because He writes it down doesn’t change that it will be… as is clearly evident in my initial response to you.