I do a bit of both... The guy I dated the longest (and am still conflicted about) I had a similar box of items... uh... mostly shredded in a fit of rage... and then when I was sure I had all the reminders of the pain I burned it (safely in a bonfire) in a fit of rage. On the other side... I still have the beautiful wool sweater he gave me when we went sailing together and a really hot picture of him that looked like a calvin cline add!

All in all the relationship was unhealthy for me and needed to end. BUT the wonderful memories don't have to.

BTW... the picture and sweater were in a box in my garrage for 2 years before I could enjoy them without crying. begrudgingly I have to admit that the afternoon we spent sailing was one of the best of my life.

relationships are not black or white so break-ups aren't either. Take your time and grieve as you need to.

My opinion... It sounds like you have good and bad memories all mixed up in that box, all mixed up in you. Until I could sort the good from the bad I wouldn't do anything that can't be undone.