All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad, sallallaahu ‘alayhi wa sallam, is His slave and messenger.
The father is obligated to provide the food, clothing and accommodation of his children according to reasonable terms as we have already clarified in Fataawa 163965 and 168563.
School fees are included in this as stated by some scholars. For example, Nihaayat Al-Muhtaaj fi Sharh Al-Minhaaj, which is one of the books on the Shaafi’i School of jurisprudence, reads: “...And he [the father] is obligated to enroll him [his son] in a Maktab … which is the name for the place of education … and another place to learn a profession; so he learns to read from the former and a profession from the latter as appropriate to the condition of the son… .” [End of quote]
Therefore, the father should not be stingy about this as long as he is able to do so, because children's success in life is comforting to the parents and is to their interest.
Therefore, we advise both of you to have mutual understanding in achieving what is beneficial for the children. You may seek the help of friends and relatives, or any other party who you believe that your ex-husband would listen to, to help you reach an agreement concerning this matter.
If you do not have a husband at the moment and you are able to go back to your ex-husband, then we advise you to do so. The separation of the parents has bad and serious effects on the children regarding their good upbringing and education. This sometimes requires the parents to sacrifice for the sake of the children.
Allaah Knows best.