Should i tell my cousin?

My uncle has a bto and recent years made a will (or rather one of my aunt made him do that and put 1 of her sons as the beneficiary) thing is the uncle has a son himself and he doesn't know of this made up will let alone that he's not the beneficiary. The aunt never mentioned this to the uncle son either. I feel kinda unfair to this but then again I know the aunt will be very angry at me should I say anything. Should I tell my cousin whom I hardly interact with? Or just like pretend nothing happened?