Is it permissible for a woman to seek divorce from her husband who marries and divorces frequently, and who often abandons her and travels, while she cannot bear this? And would she be considered unjust to her husband or to his other wife, and is she sinful for informing the other wife about her husband's past, which led to her divorce? And what should she do?

What you did by inciting the other wife and informing her of your husband's past, and your intention to divorce, is a reprehensible act. The Messenger of Allah, peace and blessings be upon him, forbade inciting a woman against her husband. Your intention was revenge, and this is an injustice to your husband. What is incumbent upon you is to repent to Allah, and to seek forgiveness from your husband if that does not lead to a greater harm; otherwise, supplicate for him and seek forgiveness (for him). The husband is commanded by Islamic law to treat his wife kindly, and it is not permissible for him to abandon her without a legitimate reason. A wronged woman has the right to seek divorce or khul', but she should not forget that separation may not be in her best interest, especially if she has children from him, as the family may become dispersed and the children may be lost.