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.
The husband is obliged to spend on his young children and on his children who have no money. He is obliged to spend on them even if he has divorced their mother, as we have already highlighted in fatwa 178803. Also, please refer to fatwa 85593.
Spending on his children should be according to his ability, Allaah says (what means): {Let a man of wealth spend from his wealth, and he whose provision is restricted - let him spend from what Allaah has given him. Allaah does not charge a soul except [according to] what He has given it. Allaah will bring about, after hardship, ease.} [Quran 65: 7]
The fact that you left a house for your children does not exempt you from spending on them. The house is part of spending on them. However, if you have other children, then it is not permissible for you to let them own that house except with the consent of your other children if they are of sound mind and are adults because it is an obligation to be just when gifting your children according to the preponderant opinion of the scholars, as explained in fataawa 164019 and 119032.
Also, the husband is obliged to spend on his wife, even if she is rich, as clarified in fatwa 168551. Hence, the husband is obliged to give everyone his right. If we presume that spending on the wife coincides with spending on the relatives in a way that the husband is not capable of, then spending on his wife comes first. Ibn Qudaamah said in Al-Mughni:
“If a person does not have in excess of his needs except what is enough for spending on one single person while he has a wife, then he should spend on his wife and not on his relatives, as the Prophet said in the hadeeth reported by Jaabir 'If any of you is poor, then he should start by spending on himself, and if anything remains, then he should spend it on his family (i.e. wife and children), and if he has anything left, then he should spend it on his relatives.' This is because spending on the relatives is a consolation while spending on the wife is an obligation as a way of compensating her, so spending on the wife comes in priority over mere consolation. It is for this reason that spending on the wife is an obligation regardless of whether they (the husband and wife) are solvent or are in financial difficulties, while spending on the relatives is not the same thing. Also, spending on the wife is an obligation for one's need (for having a wife), so it comes in priority over spending on the relatives just as spending on himself comes in priority.”
On the other hand, the husband should not take from the money of his wife to give to his children unless she donates it out of her own free will.
The children have the right on their father to keep ties with them, nurture them and take care of them, even if they are in the custody of their mother. However, he must avoid entering upon their mother or being alone with her without the presence of one of her mahrams (permanently unmarriageable kin) if she is irrevocably divorced from him and thus became a non-mahram to him.
Allaah Knows best.