'Self' and 'Other' are two empty concepts, each totally lacking in verisimilitude, making sense only in their interdependence as appearances in mind.
There is no self, there is no other-than-self. No thing of the kind exists at all except as phenomenon.
All they are is what they are when they are not anything. Objectively figments, they represent mind cognising them within itself, and the cognising of them is itself their phenomenal being.
To differentiate between them is absurd; to be identified with one and to regard the other as independent is ridiculous; to claim one and to reject the other is the purblind nonsense of identification - for all each is, is whatever I am, and whatever I am is all that anything is.
'That' is no other than 'this', and 'this' is no other than either, for each is the cognising of both, and such is what I am.
Self and other are images extended in conceptual space and in conceptual time (duration), rendered apperceptible as phenomena thereby, and their only being lies in their interdependent apprehending.
Ta o sage, differentiation into self and other-than-self is just the 'let's pretend' of children playing at being Judy and Punch.