All perfect praise be to Allah, The Lord of the worlds. I testify that there is none worthy of worship except Allah and that Muhammad is His slave and Messenger.
If your father used to insult your mother and beat her, then there is no doubt that he had committed a great evil by that, as he is Islamically commanded to be kind to her, as Allah says (what means): {And live with them in kindness. For if you dislike them - perhaps you dislike a thing and Allah makes therein much good.} [Quran 4:19]
If he did not spend on your mother while she was married to him and on those of you whom he is obliged to spend on – the young children who have no money – while he was/is able to spend on them, then he is sinful because of this negligence.
Abdullah ibn ‘Amr, may Allah be pleased with him, narrated that he heard the Prophet say, “It is enough a sin for a person not to provide for his dependents.” [Ahmad and Abu Daawood]
It should also be mentioned that it is permissible for a wife to take from her husband what would suffice her and her children without his knowledge if he refuses to spend on them. ‘Aa’ishah, may Allah be pleased with her, reported that Hind bint 'Utbah, may Allah be pleased with her, said, “O Messenger of Allah! Abu Sufyaan is a stingy man who does not give me and my children what suffices us, except for what I take from him without his knowledge.” So the Prophet told her, “Take what will suffice you and your children within reasonable limits.” [Al-Bukhaari and Muslim]
There is a difference of opinion among the scholars about whether an adult person is entitled to be provided for (by his father) if he has no money or earnings.
Indeed, you did well by being kind and dutiful to your father despite his bad behavior and abuse, because the father has the right upon his children that they be kind and dutiful to him even if he is abusive. Allah commanded us to be kind and dutiful to the father even if he is a non-Muslim; Allah says (what means): {But if they endeavor to make you associate with Me that of which you have no knowledge, do not obey them but accompany them in [this] world with appropriate kindness.} [Quran 31:15]
So may Allah reward you well for that.
If your uncles have done the bad deeds that you mentioned, then they have committed a great evil. The help of some wise and righteous people whom they would likely listen to should be sought so that they would repel their harm from your mother. Nevertheless, your uncles are part of your family, so it is not permissible to sever the ties of kinship with them, even if they are abusive; rather, you should keep the ties with them, be patient with them, and advise them.
Abu Hurayrah, may Allah be pleased with him, reported that a man came to the Prophet and said, “O Messenger of Allah, I have relatives with whom I uphold the ties of kinship, but they cut me off; I treat them well, but they mistreat me; I am patient with them, and they harm me.” The Prophet said, “If it is as you say, then it is as if you are stuffing hot ashes [in their mouths], and you will continue to be supported by Allah against them so long as you continue to be like that.” [Muslim] [“Stuffing hot ashes” means that your kindness to them in spite of their harshness is like feeding them hot ash for the sin that they are committing by their evil deeds].
The matter is not clear with regard to the relation of your uncles to your father’s money: was it a trust deposited with them, or was it a gift from your father to them?
In any case, what we can say here is that your father has the right to dispose of his property as he wishes as long as he is of sound mind and chooses to do so out of his own free will. You have the right to ask him only about what he is Islamically obliged to fulfill to you. As regards what he gifted to his brothers with his own will and which they took possession of, then it has become their property.
However, it would have been better for him if he had left something for his heirs, pursuant to the advice of the Prophet to Sa’d ibn Abi Waqqaas, may Allah be pleased with him, “It is better for you to leave your heirs wealthy than to leave them poor, begging the people.” [Al-Bukhaari and Muslim]
Allah knows best.