A little bit of context:
Peter and Kevin were working on a mission together, and Peter had already planned (He was looking forward) to betray Kevin by the end of the mission. Kevin did not know Peter's intentions at the time but had suspicions that Peter was going to betray him.
And when it finally happened and Peter betrayed Kevin, Kevin then realized that he should have been more careful of Peter.*
Now, what would be appropriate tense to use in the moment after Kevin got betrayed?
Kevin: "Damn it, you had been looking forward to this moment!!" ("this moment" as in betraying him)
(The act of looking forward ended when Peter betrayed Kevin) so I think this tense would be the correct one.
Kevin: "Damn it, you have been looking forward to this moment!!"
I think the Past Perfect would be the correct tense since now the act of looking forward has already ended (He's been betrayed). It's now in the past, not an ongoing event. Therefore the present perfect is not appropriate because it is not an ongoing event.
I am not sure whether I am correct or not though.