Psychology tells us that forgiveness is a process like all other things and you cannot change your perspective or attitude towards someone overnight. The duration and difficulty will vary significantly, it can be equally applied to all levels of pain. In many ways I think it takes more strength to forgive staying angry and bitter is easy. It's not a natural instinct to see someone for their mistakes, accept their mistakes and forgive them for those. Giveness is pretty powerful. It's the harder path to choose. And when you have that kind of philosophy and that state of forgiveness you can feel that peace as well.