First of all, the Prophet (peace and blessings be upon him) said: “Among lawful things, divorce is the most hated by Allah.” (Reported by Abu Dawud). Thus, the spouses should avoid divorce to the best of their abilities, and if they have difficulties and problems, they should try to work out their differences and seek help from their relatives, friends or professional counselors. They should also consider and think of the future of their children and the destructive effects of divorce on their children’s future. However, if the differences are irreconcilable, divorce is then permissible, but it should be done in a decent manner.
In this regard, Allah the Almighty says: “When you have divorced women, and they have reached their term, then retain them in kindness or release them in kindness. Retain them not to their hurt so that you transgress (the limits). He who does that had wronged his soul. Make not the revelations of Allah a laughing stock (by your behavior), but remember Allah’s grace upon you and that which He hath revealed unto you of the Scripture and of wisdom, whereby He doth exhort you. Observe your duty to Allah and know that Allah is Aware of all things.” (Al-Baqarah: 231). The Prophet (peace and blessings be upon him) says, “No harm shall be inflicted or reciprocated in Islam.” (al-Mu’jam al-Awsat)
Second, one of the matters on which there is scholarly consensus is that the woman is more entitled to custody of the child so long as he has not reached the age of discernment, as the child at that stage needs the kind of compassion and care that only the women can give, but this right is forfeited if the woman remarries, because she will be distracted by her new husband from taking care of her child, and because there is a conflict of interest between the child and the new husband.
Ibn al-Mundhir (may Allah have mercy on him) narrated that there was scholarly consensus that the mother’s right to custody is forfeited if she remarries. This is indicated by the hadith of `Abd-Allah Ibn ‘Amr (may Allah be pleased with him) according to which a woman said: O Messenger of Allah, my womb was a vessel for this son of mine, and my breasts gave him to drink, and my lap was a refuge for him, but his father has divorced me and he wants to take him away from me. The Messenger of Allah (peace and blessings be upon him) said to her: “You have more right to him so long as you do not remarry.” (Narrated by Ahmad and Abu Dawood).
Third, maintenance of children is obligatory upon the father according to scholarly consensus, whether he keeps his wife or divorces her, and whether the wife is poor or rich. So she is not obliged to spend on the children if the father is around. If the children are in the custody of a divorced woman, then their father must support them, and the mother who has custody of a child who is still breastfeeding has the right to ask for payment for nursing the child.
Maintenance of children includes accommodation, food, drink, clothing and education, and everything that the child needs, and it is to be based on what is reasonable, paying attention to the husband’s situation, because Allah says: “Let the rich man spend according to his means; and the man whose resources are restricted, let him spend according to what Allah has given him. Allah put no burden on any person beyond what He has given him. Allah will grant after hardship, ease” [al-Talaq 65:7]
It is also worth mentioning that this varies from one country to another and from one person to another. If the husband is rich then he must spend according to his wealth, and if he is poor or of moderate means, then he must also spend according to his means. If the parents agree upon a specific amount of money, whether it is great or small, then that is up to them. But in the case of dispute, the one who should decide about what is to be given is the qadi (the judge).
According to the scholarly consensus, the payment for breastfeeding the child is the legal right of a divorced woman over her ex-husband, hence, It is permissible for her to demand her ex-husband for the payment.