Re: If you found yourself aboard the Refitprise during TMP...
The universe Spock and Nero came from would continue without them, after all existence was around long before the both of them were on the scene.
Honestly, we don't know whether their timeline continued or ceased to exist when they exited it. The movie doesn't really tell us one way or the other.
"If we're going to be damned, let's be damned for what we really are." - Jean-Luc Picard, "Encounter at Farpoint"