"Never fight with a pig, you'll both get dirty, and the pig likes it."
Be good enough to forgive a person but don't be a stupid to trust them again, Those who tries to pull you down or those who wants to compete with you or try to pull you in a rat race which was meant to fool you or make fun of you, such peoples are already lower than you they don't have any ethics or standards.
Such peoples pulls others also in there rat race which have been designed in such a way so that they can teach u the same waste which they have learnt so far.
Simply avoid such evil minded souls before they turn you into mud.