I have my share of unpleasant memories, but on the whole I think they are part of who I am. So even the really nasty ones have a lesson attached, unpalatable as it may be.
In time I will probably forget most things anyway. I can barely remember why I went upstairs, or where I left my shoes.
But some things contribute little to the greater good. And this is one of them: I can find no lesson to learn or silver lining in this particular piece of hideousness.