Can I special build after rolling the dice?
There are 2 possibilities of how to handle this here, and neither one would allow your opponent to build the road instead of you.

1) Have the special building phase; pretend like you never rolled. In this case, because it would be your turn next, you would get the first turn during the special building phase to build where you want.

2) Don't allow the special building phase; because it's too late for that. The special building phase would happen before your turn; now that you've rolled, it is your turn. People missed their chance to build. In this case, you can just build during your turn like normal.

The rules don't clearly state whose responsibility it is to ensure that people get a chance to build in the special building phase. However, they do state that the phase does happen. It's not optional (though each player building during the phase is optional). So you technically shouldn't have rolled the dice yet; because it wasn't your turn yet.


  The Special Building Phase occurs just after the end of your turn (i.e., between player turns).


But in a friendly game; we either do a quick check ("is anyone building in between turns?") or just assume that no one is unless someone speaks up ("hold on, I want to build before you roll").

Either way, I don't see any situation in which the rules would imply that you don't get a chance to build your road before your opponent; you have first chance at it.