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 is His slave and Messenger.
Your ex-husband has become a non-Mahram to you, and it is not permissible for a woman to speak with a non-Mahram man except for a need and provided that the religious pre-conditions are met as we clarified in Fatwa 85201.
So, if you need to speak with him, this is permissible but you should not be in seclusion with him or in a place of suspicion or involved in any other thing that contradicts the Sharee’ah or could be a reason for temptation.
It should be mentioned that education fees is not included in the obligatory spending (upon the husband for his wife) according to the view of many scholars although some of them are of the view that it is included.
We also wish to mention that a husband is not obliged to spend on the children of his wife from a previous marriage and we have already clarified this in Fatwa 86141.
Allaah Knows best.