Can she ask her husband to use a condom to protect herself if he marries another wife?
Question

                In this day and age a lot of people step out of there marriage and make kids that r not there husband and bring back S.T.Ds so can I ask my husband to use condoms with me to protect myself if he take on a second wife.
Praise be to Allah.
      Firstly: 

    Zina is a major sin, great calamity and the worst of conduct, 
    and its consequences in this world, in the Hereafter and in the grave are 
    severe. 

    Allah says (interpretation of the meaning):

    “Made lawful to you 
    this day are At‑Tayyibaat [all kinds of Halaal (lawful) foods, which Allaah 
    has made lawful (meat of slaughtered eatable animals, milk products, fats, 
    vegetables and fruits)]. The food (slaughtered cattle, eatable animals) of 
    the people of the Scripture (Jews and Christians) is lawful to you and yours 
    is lawful to them. (Lawful to you in marriage) are chaste women from the 
    believers and chaste women from those who were given the Scripture (Jews and 
    Christians) before your time when you have given their due Mahr 
    (bridal-money given by the husband to his wife at the time of marriage), 
    desiring chastity (i.e. taking them in legal wedlock) not committing illegal 
    sexual intercourse, nor taking them as girlfriends. And whosoever 
    disbelieves in Faith, [i.e. in the Oneness of Allaah and in all the other 
    Articles of Faith i.e. His (Allaah’s) Angels, His Holy Books, His 
    Messengers, the Day of Resurrection and Al‑Qadar (Divine Preordainments)], 
    then fruitless is his work; and in the Hereafter he will be among the losers”

    [al-Maa’idah 5:5]. 

    Ibn Katheer (may Allah have mercy on him) said: 

    Just as it is stipulated that women be chaste -- which means 
    refraining from zina -- it is also stipulated for men; a man should also be 
    chaste. Hence Allah says “not 
    committing illegal sexual intercourse”, referring to adulterers 
    and fornicators who do not refrain from committing any sin and do not 
    control themselves. “nor taking them 
    as girlfriends” means: limiting himself to one woman or mistress. 
    End quote. 

    Tafseer Ibn Katheer, 3/43 

    Shaykh al-Islam [Ibn Taymiyah] (may Allah have mercy on him) 
    said: 

    If a woman's husband commits zina with another woman, and 
    does not distinguish between halaal and haraam, his intimacy with that woman 
    is the same as the intimacy of the zaani with a woman with whom he is 
    committing zina, even if no one else is intimate with her, because one of 
    the forms of zina is taking a girlfriend or mistress. 

    End quote. Majmoo‘ al-Fataawa, 32/145 

    Shaykh Ibn ‘Uthaymeen (may Allah have mercy on him) was 
    asked: 

    A woman saw her husband committing zina -- Allah forbid. What 
    should she do? 

    He replied: 

    She should advise him, especially if that was the first time 
    and she has children from him. But if he persists in doing that then she 
    should seek an annulment of the marriage. However, in general, she should 
    weigh up the pros and cons and decide on that basis. End quote. 

    Thamaraat al-Tadween min Masaa’il Ibn ‘Uthaymeen, 
    p. 112 

    See also the answer to question no.
    115107 

    Secondly: 

    The wife does not have the right to ask her husband to use 
    condoms during marital relations, unless there is a reason for doing that. 
    The fact that he has married another woman in a legitimate shar‘i marriage 
    does not make it permissible for her to do that, unless it is clear that the 
    husband himself has a disease, such as AIDS and the like, which could be 
    transmitted to her through sex, or it becomes clear that the other wife has 
    a disease of this type, or the husband was in a haraam relationship outside 
    of marriage. In that case she has the right to ask him to use condoms, so as 
    to ward off the harm that is thought to exist in him, until it becomes clear 
    that he is free of that. If it becomes clear that he is healthy and there is 
    no obvious source of danger of transmitting disease through him, then she no 
    longer has the right to ask him to do that. If it becomes clear that he does 
    have a disease which could harm her or be transmitted to her, then she has 
    the right to ask him to carry on using it; indeed, in that case she has the 
    right to ask him to annul the marriage, if his sickness poses a danger to 
    her and it is something that it is difficult to treat or avoid, such as AIDS 
    and the like. 

    See: al-Ahkaam al-Shara‘iyyah al-Muta‘alliqah bi Marda 
    al-AIDS, by Dr. ‘Umar Sulaymaan al-Ashqar, in Diraasaat Fiqhiyyah fi 
    Qadaaya Tibbiyyah (1/25 ff). 

    And Allah knows best.