What is the ruling on the money my wife's brother pays me monthly, knowing that part of his money comes from selling forbidden tobacco, and it is mixed with lawful money? And how should I dispose of this money? And is it permissible to sponsor an orphan with the money that must be given out if part of it is unlawful?

You must repent to Allah for your involvement in selling the forbidden tobacco, and dissolve your partnership with this man if he does not abandon its sale. You are required to dispose of the profits resulting from the sale of tobacco, because trading in tobacco is forbidden and its earnings are forbidden, as the Prophet (peace be upon him) said: "Indeed, when Allah forbids a thing, He forbids its price." It is not permissible for you to remain in this sin with the intention of getting rid of the forbidden portion for sponsoring an orphan; rather, what is obligatory is to abandon the forbidden thing completely.