forgiveness
re: http://www.salsagang.com/modules.php?name=Forums&file=viewtopic&t=249
"Forgiveness is in vain if you can't forget".
There is a scale of things that range from totally unforgivable, to no big deal. What you put on this scale is dependent on each person's upbringing and values. Also, time is an immense healer. You change in that time, hopefully grow more mature, and you might see that this act that was not forgivable is now sitting on a different place on that scale.
There is no such thing as "have to" forgive, but personally unless it's an extreme situation, I would rather forgive and forget and have the person in my life, rather than lose a friendship. You get upset at people that are important to you. Those that you barely know, you don't care too much to forgive. So, really, forgiveness is like a gift to yourself for having that person in your life.
Emotions are what make us humans, and whether they are negative or positive, it's just a needed contrast to distinguish what suits you best.