Is Talaqnaama valid for Divorce

I am a Muslim belonging to the Sunni sect. I was married for the last 4 years and have one son. For last 2 years I am working abroad while she is in India. We always had quarrels with each other over the phone. She has always been pushing me to live separately from my parents which i did not agree to. She would always emotionally blackmail me. 14 months ago, she went to her mother's place with my son refused to comeback to my home inspite of repeated requests. I sent her a lawyer's notice for her to return. She responded to my notice with a counter notice accusing me of demanding dowry. I replied to this accusation by a lawyers notice and applied for Talaaq through Qazi. Talaaq was approved and I have the approval from Wakf. Iddat maintenance was also paid as per Islam. Is this Talaaq valid as I am getting conflicting answers on this from different sources. Can my wife challenge this divorce? I am okay to pay reasonable maintainance for supporting my son.