This is from some movie, I think ? The person saying it is about to finally kill his foe/enemy. (He has a weapon pointed on the guy he is speaking to"). He is essentially saying "I'm going to kill you and it won't be in Heaven you will end up in, it'll be Hell" Saying "St Peter is going to meet you" is saying "You're going to be dead" (by the speaker's hands in this case) Adding "but in Hell" is saying "For all the bad stuff, etc you've done, it will be Hell where you will end up (not Heaven).