How can one get rid of arrogance and self-admiration, and is repentance accepted after years of being distant from God?

The conditions for sincere repentance are: regretting the sin, abandoning it, and resolving not to return to it.

What you feel of pride and self-esteem is strange for someone who dared to disobey God, then God guided them to repentance, because the original state of such a person should be one of a broken heart and a humble gaze before God Almighty.

To treat the malady of pride, remember that this disease is destructive to its possessor, and that pride is an attribute belonging solely to God, the Exalted. Remember human weakness, need, and poverty. Accompany righteous and humble women. Read the biography of the Prophet, peace be upon him, and frequently visit the sick and those afflicted, for this breaks the heart and instills humility.