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.
Indeed, you did well by giving back to your wife what you had taken from her unjustly.
As regards what your father had taken from that money, then if he had taken it from you as a loan which he will give back to you, then it is a debt which he is obliged to pay back to you and you have the right to ask for it so that it will be paid back to you (after your father's death) from his inheritance before its division.
However, if you volunteered to your father with the money which he had taken from you, then you have no right to ask him to reimburse you.
As regards the land, you have absolutely no right to it unless you had given the money to your father so that he would buy the land for you, in which case, he cannot give it to anyone else; apart from this probability, the land is your father’s and you are only entitled to the money that he had taken from you if you did not gift it to him. Hence, the piece of land that your father had given to your sister from that land during his life when he was sane and in good health, is her own property.
The same thing applies to the rest of the land, if he had gifted it to your mother and she possessed it before his death, then it is hers. Also, if he had registered it in her name as a will and the like without rendering her as its possessor in his life, then it is considered as part of the inheritance of your father and it should be divided among his heirs because there is no will for an heir unless all the heirs approve of it.
On the other hand, if we presume that the father had made his wife the possessor of the rest of the land during his life, then she has no right to give it to her daughter out of favoring her over her other children. That is because it is an obligation on the parents to be just between their children when gifting them according to the most preponderant opinion of the scholars unless there is a sound reason for favoring a child over the other, like due to him/her dutiful and kind to his/her parents, or being righteous while the other child is dissolute, or due to him/her being in need because of sickness or because of seeking religious knowledge and so forth.
However, in case the mother favored her daughter with a gift without a sound reason, then it is not permissible for the daughter to accept that gift (from her mother who is still alive), and she is obliged to share it equally with her siblings as a way of achieving justice and avoiding injustice.
As regards what your father had gifted to some of his children (before death), even if he did so without a sound reason, then the gift becomes effective once he dies according to the most preponderant opinion of the scholars even if there is injustice and sin in it.
In any case, you are not permitted to cut relations with your mother or desert her, but it is permissible for you to advise her in a good and soft manner without raising your voice or disputing with her or mistreating her in word or deed. Even if she is wrong, you are still obliged to be kind and dutiful to her, and it is not permissible for you to mistreat her because she mistreated you. Rather, you should keep ties with her and not desert her, and if you advise her and admonish her, you should do so in a soft and gentle manner; for more benefit, please refer to Fataawa 85873, 85041 and 87019.
Allaah Knows best.