The ego is illusory but not non-existent by Atman Nityananda / blog
If the ego doesn’t exist then:
Who or what identifies with the body or with some object?
Who or what desires pleasure?
Who or what wants to avoid pain?
Who or what causes such a havoc and suffering on human beings, individually and collectively?
Negation of the ego doesn’t make it non existent
The whole universe is illusory
It is true that the ego is illusory, but the whole universe and the forms (gross and subtle) in it are illusory, since everything in the universe is composed of the same fundamental powers or energies, the three qualities (gunas in Sanskrit, i-rajas, tamas and sattva.
Everything that is made of the three gunas is illusory. That is, all gross and subtle forms, that is the whole universe.
What does it means illusory?
We cannot find and perceive the ego
We can recognize, be aware of and observe the ego as any other egoic tendency, thought or emotion. There is no doubt about it. A trillion objections cannot override my experience of 15 years (up to this point). I have read that others have also made this observation.
Is the ego the identification with the body or thoughts?
The idea that the ego is the identification with the body or thoughts is also false. It is the ego that identifies with the body and thoughts. Without the ego there can be no identification with the body, thoughts, ideas, emotions, objects or any form.
Ego as the agent or doer
Ego and the Three Gunas
Depending on the nature of our mind and ego (sattvic, rajasotamasic or tamasorajasic) and the state of our mind at any given moment, there is mechanical thinking or conscious thinking, emotional thinking or intellectual thinking, identification with emotions and thinking or detached witnessing of them. Moreover, passionate thinking, agitated thinking, distorted thinking, clear and calm thinking, etc. depending on the quality (guna) that prevails in our mind.
See below a map that presents the most fundamental aspects of Ego.

Read more on the nature of ego: The Expressions of the ego