My husband left me and our son. Can he come back and take our son without my permission?

My husband left me and his son a year and a half ago and traveled back to Russia without even canceling his work visa.

He contacted me recently claiming he divorced me under an exceptional condition in Russia so that he doesn't take any financial responsibility towards his son.

I am the sponsor of my son and I pay everything for him for the last 4 years. He is 7 years old and goes to a good school in Dubai.

My question is if his father decided to come back again as a tourist, will he be able to issue my son any exit pass or even be able to take him out of the airport without my permission?

My son's passport is with me.