You may play Temporal Vortex on the dilemma to make it disappear for three turns. If not, carry out the results. This ship battle is an action which may be responded to by playing Hugh to nullify the Borg Ship's attack for the rest of the turn. If the attack is not nullified, resolve as for any ship battle, calculating hits and direct hits, applying damage, and discarding destroyed cards. It all depends on what kind of a response is made.
Responses fall into three general categories.
If the action was a card play, the nullified card is discarded. Examples of responses that nullify an action are the play of Amanda Rogers to nullify an interrupt, and the use of Dathon's skill to nullify Shaka, When The Walls Fell upon encounter. If a response modifies an action, then the action resolves, but probably in a different way. Examples of responses that modify an action are the play of Howard Heirloom Candle to double the effects of Anaphasic Organism and the use of Madred's skill to add 1 to the points you score for an interrogation. Again, there is no effect on the initiation of the action.