Is Atheon really dead?

I like to think of the vault-reality relationship as a highway. The highway itself is space-time. The direction if traffic is time and the cars are people and things. There are multiple off ramps. These exits are the entrance to the vault. The vault is where ever the exits lead to so who the f knows lets make it a McDanks or something. you got off the highway at one point and entered the vault. Time dosen't flow in the vault and space is a warped concept. Let's say there's another highway that runs the opposite direction along side the original one. This will be an alternate dimension. The exit in the other highway still leads to the vault. Theoretically, if I were to get off at one point and do something in the vault, then my past self would get off the highway and see me change the vault because the entrance in his time still lead to the same vault and becuase time isn't a factor, the effect would have no point in time to happen. So if anything happens it the vault, it has happened, always will happen, and is still happening. If we killed Atheon in the vault, he never existed in the first place. I'm pretty sure I'm wrong about this entire thing though. In short, there was only ever one atheon, and we killed it.