Often times when we're mad, or get hurt, we keep it in. Unfortunately anything that isn't dealt with will soon surface to the ground, usually in the wrong time (since we fail to allocate an appropriate time), and in the wrong way.
When something hurts us - really hurts us - whatever bad experience it is, it changes our lives. It changes the way we interact with others: those that have done us wrong, those we've done wrong, those who stay behind while others leave, those who remind us of others gone, and mainly... ourselves. We ourselves change to accommodate a place for all of this pain, these lingering tragedies. Our lives become the sum of our calamities.
Take the time to deal with whatever ails you, for it, uncured, will cripple your life.