My advice in this situation is either a) take your army out of the area and conquer elsewhere, or b) Attack them all. I'm heavily favoring the second one since taking the Iberian peninsula is crucial to establishing your Spanish empire. Since you just won the Crusade, you have a powerful general near Antioch with experienced units, so you could probably take it back from Portugal with ease. As for Portugal's home turf, you should be able to muster two armies to take that. I recommend taking it all in the same turn so the Pope doesn't stop you before you can finish them off. Nothing's worse than a papal timeout making you go sit in the corner and think about what you did.