In the prime universe, Romulus was destroyed when the Hobus star went supernova (exploded) and began expanding and literally eating everything in it's path, and was only stopped by Spock sacrificing himself.
In terms of the event in the Star Trek movie everything that happens occurs in an alternate reality. Romulus was never destroyed in the prime continum because if it was then ir would create hundreds of pieces of discontinuity.
ex: romulans in the dominion war
star trek nemesis
TNG episodes birth right,unification
Romulus was destroyed in the primary universe in 2387 by the Hobus supernova, a supernova that sent massive shockwaves through subspace, and Spock used red matter to create a singularity to contain the explosion before it could destroy other planets. He would have stopped it in time to save Romulus, but the Romulan Senate and the Vulcan Science Academy didn't provide the needed support. His ship, the Jellyfish, had trans-metaphasic shielding that could survive the shockwaves and a star. Nero used his modified ship, the Narada, to fight several Federation ships and Spock. He blamed Spock and the Federation for Romulus's destruction. They fell into the red matter singularity and ended up in the past, Nero in 2233, and Spock in 2258. Nero destroyed several ships, the Kelvan, and killed James Kirk's father. The slaughtering attack and George Kirk's death changed the design of the original Enterprise and caused James Kirk to enter Starfleet later on.
Time travel through a red matter singularity and changing the past can create an alternate reality, a timeline that coexists with ours. Nero's time travel didn't change the main universe's history, due to the massive paradoxes involved in timetravel through quantum singularities and changing the past. Romulus has been destroyed in our universe, and it still exists in the alternate reality, atleast until 2387, when it would supernova unless it would be attempted to be stopped.
To confirm, Romulus is destroyed in the prime universe in 2387, and it hasn't been destroyed, atleast not yet, in the alternate reality.
The role Romulus played in the main history is unchanged, but could be different in the alternate reality.