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.
There is no doubt that it is an obligation to obey your father in righteousness but doing so in sinful acts is strictly prohibited. Allaah Says (what means): {And We have enjoined on man to be good and dutiful to his parents, but if they strive to make you join with Me (in worship) anything (as a partner) of which you have no knowledge, then obey them not….} [Quran 29: 8] Besides, the Prophet said: "Obedience is required only in what is permissible." [Al-Bukhari and Muslim]
Since the property of your father is a mixture of lawful and forbidden earnings, then there is no objection to your eating from it although it is better not to do so.
Also, there is no harm in helping your father in selling and buying within the limits of what is lawful but it is forbidden to help him in what is forbidden as Allaah Says (what means): {…but do not help one another in sin and transgression. And fear Allaah. Verily, Allaah is Severe in punishment. } [Quran 5: 2]
We advise you to do your best to convince your father to give up forbidden transactions by clarifying to him in a wise, soft and gentle manner that ill-gotten earnings are a source of harm and evil in this life and the Hereafter. Tell him that any human flesh that grows from what is forbidden deserves to be thrown in Hell and that the person will remain standing on the Day of Judgment until he is asked about four things among which is his wealth from what he earned it and in what he spent it. Tell him also that the briber, the bribed and the Riba dealer are all cursed and kept away from the Blessings of Allaah. We hope Allaah will guide him to the right path.
As far as you are concerned, you should look for a lawful job from which you can spend on yourself. But this does not mean that you should sever ties with your father. On the contrary, you should continue helping him in that which is lawful.
Allaah Knows best.