[He feels it going, and he panics.

So:]

You want the truth? Remember when that girlfriend of yours OD'd? Remember how Mike disappeared? And the kid — how do you think he got so sick? I don't know what you're assuming I did to Walter, because I didn't do anything, but I'm telling you right now: whatever happens to that son of a bitch, whether it's done by my hand or someone else's — he deserves it.