@existential potential,
Nice equation: ontological self = situational self.
I'm sure we never have one without the other, but theoretically speaking, an ontological self is that which is felt as inside vs. the outside worlds while situational self, while it always occurs in a setting, is identified by its assigned content, e.g., a man, a father, an American, a barber, youngster, citizen, etc. etc..
Perhaps we can say that the ontological self is the individual's ego-self, his private "metaphysical" identity while his situational selves are public social-culturally assigned identifications.
I agree that ultimately there is no "real" self.