Praise be to Allah.
It would have been better for you and your husband to refer what happened between you of matters having to do with marriage, divorce, the mahr and ‘iddah before deciding whether to end the marriage or carry on with it, to a shaykh near you, or to an Islamic centre run by people who you trust, or to wait until you asked someone whom you trusted, even if that was someone far away. You should not have taken the rulings on these issues from people or from a lesson given by a shaykh in a mosque. This is the advice that we always give to spouses who have problems, and we advise them to refer matters of marriage and divorce only to an Islamic judge (qaadi) or to one who plays the same role in countries where there is no Islamic legal system.
With regard to divorce before consummation of the marriage, the following details apply:
If a divorce is issued to the wife before consummation of the marriage and without having been completely alone together in such a manner that consummation of the marriage would have been possible, then she does not have to observe ‘iddah, and she is entitled to half of the mahr that was agreed upon. If no mahr was agreed upon, then she is entitled to some payment, according to how well off he is. And he cannot take her back except with a new marriage contract and mahr.
If a divorce is issued to the wife before consummation of the marriage but they have been completely alone together in such a manner that consummation of the marriage was possible, then the majority of Hanafi, Maaliki, Shaafa‘i (according to the earlier view of their madhhab) and Hanbali scholars are of the view that she must observe ‘iddah and she is entitled to the mahr in full. As far as taking her back is concerned, the majority of Hanafi, Maaliki and Shaafa‘i scholars are of the view that he cannot take her back except with a new marriage contract and mahr.
As you (re)married in that manner – i.e., with a new marriage contract and mahr – then at present you are a wife to him according to sharee‘ah, and he is your husband; the marriage contract between you is valid, with all its shar‘i implications, and it is not permissible for either of you to undermine any of its conditions, if the conditions are Islamically acceptable. Moreover, it is not permissible for him to ask you to give up some of your rights, unless you do that willingly, not as a result of compulsion or embarrassment.
It was narrated from ‘Uqbah ibn ‘Aamir (may Allah be pleased with him) that he said: The Messenger of Allah (blessings and peace of Allah be upon him) said: “The conditions that most deserve to be fulfilled are those by means of which intimacy becomes permissible for you.”
Narrated by al-Bukhaari, 2572; Muslim, 1418.
Al-Haafiz Ibn Hajar (may Allah have mercy on him) said: The words “those by means of which intimacy becomes permissible for you” mean: The conditions that most deserve to be fulfilled are the conditions of marriage.
End quote from Fath al-Baari, 9/217
It is not permissible for the husband to go back on the conditions that he agreed upon with his wife or her guardian, whether the conditions were stated verbally or in writing. If the conditions were not recorded in the marriage contract, then they are still binding on him before his Lord, may He be exalted, even if they are not legally binding. Please see the answer to question no. 126855.
To sum up:
Your first marriage ended with a valid, Islamically acceptable divorce. As it happened before consummation of the marriage and after being alone with him in such a manner that he could have consummated the marriage, then you are entitled to the mahr in full, and you have to observe ‘iddah, and you cannot go back to him except with a new marriage contract and mahr.
Your going back to your husband with a new marriage contract and mahr is valid, whether you were completely alone with him or not. Hence your second marriage contract is valid with all its shar‘i implications, and you both have to fulfil the Islamically acceptable and permissible conditions stipulated by both of you, whether they were stated verbally or in writing.
We ask Allah to guide your husband to that which He loves and is pleased with, and to guide him to adhere to what we have mentioned of rulings. If he does not agree with what we have mentioned here, then we advise you to take your case to the director of the nearest Islamic centre, or to someone near you whose knowledge and religious commitment you trust. There is nothing wrong with asking some sincere people to intervene, especially if they are from your family or his, to bring about reconciliation between you.
And Allah knows best.