Annulment and almoney money demands

I was married 20 years ago.After fight,when living alone ,Got notice of court,that my wife applied for annulment.I signed the court paper. I received annulment judgement notice,saying i will not pay almony as there was no childern,property.But after 20 years now she is demanding for money.By the time of marriage in Pakistan,an affidavit was written that i will pay 5 thousand rupees per month if she lives alone after separation. Total money for 20 years is a big amount.My question is ,do i legally bound to pay her almony after annulment,where court wrote,I will not pay any almony ,money.