Bigamous Marriage

Atty;
I recently found out from a close friend of my husband that her former marriage wasnt really legally annulled i married him 2006 and when we got married i knew that his first marriage had been cleared as he had shown me some documents proving it, thats why we pushed through the wedding. The friend had shown me documents to prove those he was just cautioning me and im just confused why is he doing so,,, but if ever this is true what should i do? if ill file a case would it be an annulment or a declaration of nulity and whats the step by step process of this? how long will the case be resolved? hope you could help me with all my questions ..
thanks ...

first, verify for yourself by requesting an nso copy of his first marriage. if it has no annotation on the margin that it has been annulled, then it is still subsisting.