Is it permissible for me to demand that my husband divorce his second wife, especially given his inability to be just between us and my suffering from this situation, coupled with my desire to preserve my home and children?

A woman does not have the right to object to her husband marrying another woman, unless she stipulated in the marriage contract that he should not marry another, in which case she would then have the right to request annulment if he does marry. It is not permissible for her to ask her husband to divorce his other wife. The husband must be just among his wives and treat them kindly. The wife must be patient and treat her husband kindly. Both spouses should strive to live together and interact kindly, as there is good in that, especially when children are present.