No you havn't thought about it. In the changed path that happens as a result of you not being born you don't go back. But in the other path, that still exists but is not active, you still go back and kill them.
Thats what i'm talking about, a 5th dimension. And just like dimensions 1,2 and 3, it is long enough to accomodate all possibilities. It doesnt have to be infinite seeing as there are a finite number of changes that can be made along its length, to accomodate all possibilities.
One day you'll see i'm right.