I'm upset that my dad plans to leave everything to his wife.
Did he tell you himself about the will?
No, and I never knew that he made a will.
While it is good to receive things from our parents after they die, it is not something that they have to do. They are free to do whatever they want with their money. People will think you are greedy if you fight for something.
But my mom is elderly and she isn't going to live forever. Logically, I should be the one to get my dad's money.
I understand your frustration, but you really aren't entitled to your fathers money. As his wife, your mom should be the one to inherit the money. Besides, your mother is elderly and needs the money more than you do since you are likely more capable of working and earning money.