assalam alykum
my daughter is mentally sick when ever i start her treatment some or other problems come to me and her treatment is stopped my question is am i commiting a sin by not dooing her treatment and i am a divorcee but i am in regular touch vith that man as i want my children get their fathers love so i talk to him in a decent manner and tll him about the welfare of kids is ithis permisible

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.

It is the father who is obliged to meet the expenses of treatment of his children and other obligatory expenses. However, you did not clarify to us the reason for which you stopped treating your daughter, whether it was a financial reason or something else. If the reason is financial, then it should be mentioned that it is the father of this daughter who is obliged to meet the expenses of her treatment in principle if he is solvent. However, if he is financially in hardship, and she has heirs other than her father, then it is her heirs who are obliged to spend on her according to the extent of their share of inheritance from her (in case she dies), and whoever is negligent in treating her while being able to do so, he is sinful.

Nonetheless, if you mean that you stopped treating her because of problems, and you became pessimistic from that, then you should know that seeing a bad omen and being pessimistic is Islamicly forbidden and the Prophet called it Shirk [associating partners with Allaah]; for more benefit, please refer to Fatwa 91474.

Therefore, this [being pessimistic] should not prevent you from treating your daughter, as regards talking to your ex-husband for a need, then this is permissible if the religious pre-conditions are met; for more benefit, please refer to Fataawa 88358 and 84468.

Allaah Knows best.