Answer:
(Fatwa: 232/184/L=1431)
Since you have given the Talaq in ignorance, therefore you will not be doing any sin. The woman got out of marital relation with you, so there is no sin on her as well if she is not ready to marry you again.
Allah (Subhana Wa Ta’ala) knows Best
Darul Ifta,
Darul Uloom Deoband
