242 The important thing is not to fuel anger, which is unhealthy for our own soul and the soul of our people, or to become obsessed with taking revenge and destroying the other. No one achieves inner peace or returns to a normal life in that way. The truth is that “no family, no group of neighbours, no ethnic group, much less a nation, has a future if the force that unites them, brings them together and resolves their differences is vengeance and hatred. We cannot come to terms and unite for the sake of revenge, or treating others with the same violence with which they treated us, or plotting opportunities for retaliation under apparently legal auspices”. Nothing is gained this way and, in the end, everything is lost.
Source: Fratelli Tutti (Vatican.va)