Some memories should be forgotten
But you can't tell now which memory has what purpose to serve. And we learn the most from our darkest hours. We are who we are today because of the choices that we made. One must make peace with himself before he can even begin to deal with a demon. Peace is such a long term feeling, it's okay to use substitutes. (And they are expensive.)
Oh well, I guess what I'm trying to say is that: Memories are the cause of all misery, but sometimes they help when nothing else can. They really are so very necessary...