Please tell me if we want to reconcile do we have to make Nikah again?

I have a very complex question to ask in the hope that you can guide us in the right direction. My husband and i went through a seperation period last year. One night at about 2am my husband called and spoke to me, he sounded very intoxicated and not in his normal sense of mind as I know he didn't sleep for days. (drugs was my reason for separation) A few days thereafter he said that he had divirced me telephonically over the phone that morning of which I don't remember clearly as i had just awoken from my sleep and he was fghting and screaming and i put the phone down on him and probably missed that part. However he was not clear as to how many times he divorced me. None the less, I sat in my iddat. Please tell me if we want to reconcile do we have to make nikkah again? My second question is just a general one. If a women is divorced and has intercourse with another man whom she is going to marry before making nikah and than he decides that he does not want to get married to her anymore. Although a huge sin has been commited can she reconcile with her ex husband?

Please treat my e-mail as confidential and anonymous. Jazakallah.