Holding a grudge will eat your insides. Eventually you will become a bitter person. All this happens because you refuse to forgive the one who hurt you. The price is too high. It's not worth it.
Grudges generate guilt.
If you have a grudge, yet willfully and continually refuse to forgive the one who hurt you, you won't feel forgiven yourself. People who hold grudges seldom sense that God is satisfied with them. You will not be able to put your finger on it, but for some reason or another you feel guilty. You think God is mad at you. You'll never feel fully forgiven and accepted by God.