He has a restaurant where he sells alcohol, and he gave her the second part of the mahr from this money
Question

                A while ago I got married to someone who worked in a foreign country. He had an import business and after 3 months he opened an Arabic restaurant where he used to sell alcohol and drink it. Is what he gave me as the second part of the mahr after divorce haraam? Please note that when he came to propose marriage to me I did not know that he drank alcohol and did not pray. He told me that he prayed and that he had done ‘umrah twice.
Praise be to Allah.There is no 
    sin on you for what you took of the second part of the mahr, even if your 
    husband’s wealth was as you describe. That is for two reasons: 
1 – The 
    scholars have stated that if a person’s wealth is a mixture of halaal and 
    haraam, and they cannot be told apart, it is permissible to interact with 
    him, buying, selling, lending and so on, just as it is permissible to eat 
    from his wealth. The Prophet  (peace and blessings of Allaah be upon 
    him) and his companions interacted with the Jews, and ate their food, 
    although their wealth was not free of haraam elements, because they dealt in 
    riba (usury) and consumed people’s wealth unlawfully. What is meant by not 
    telling the halaal apart from the haraam is that your husband’s wealth – for 
    example – combined the price of the alcohol with the price of the food and 
    permissible drinks, and the one was mixed with the other. 
2 – Some 
    scholars are of the view that wealth that is haraam because of the manner in 
    which it was acquired is haraam only for the one who acquires it, and it is 
    not haraam for the one who takes it from him in a permissible manner. 
The wealth 
    that your husband acquired from selling alcohol is haraam because it was 
    acquired in a loathsome manner. But it is haraam for your husband only. The 
    mahr that you took from him is halaal for you. 
Shaykh Ibn 
    ‘Uthaymeen (may Allaah have mercy on him) said: As for that which is haraam 
    because of the manner in which it was acquired, such as money that was 
    obtained through cheating or through riba or lying and so on, it is haraam 
    for the one who acquires it, but it is not haraam for anyone else, if he 
    acquires it from him in a permissible manner. This is indicated by the fact 
    that the Prophet  (peace and blessings of Allaah be upon him) used to 
    deal with the Jews, even though they consumed haraam things and took riba. 
    This indicates that it is not haraam for anyone other than the one who 
    acquires it. End quote from Tafseer Soorat al-Baqarah (1/198). 
Conclusion: 
    You taking the mahr from this wealth is permissible and there is no sin in 
    that. 
And Allaah knows 
    best.