Complex sentence: After giving the tritium, Harry prepares to kill Spider-Man, only to be shocked to see that it is really Peter who convinces him greater things are at stake and Harry reveals Ock's location.
Split into simpler sentences: After giving the tritium, Harry prepares to kill Spider-Man, only to be shocked to see that it is really Peter. Peter convinces him greater things are at stake, and Harry reveals Ock's location.