Personally, i'm the person to believe in karma. Although, people confuse revenge with karma. Karma is just something that happens on it's own, you don't try to force it. Revenge is something you do to get back at a person. Honestly, if someone ever did you wrong in the past, then let it be just leave it alone. Let karma work it's magic and let that other person face the consequences alone.  We all act without thinking, and that's what leads us to the mistakes we make in our lives. We forget everyone has feelings, but people want to act like their heartless. Do not hurt or undervalue people in life. We're humans we were born with wanting love, friends, and family. Let it be.