What a wonderful, thought-provoking discussion this question has created! Thank you for making us stop and think in such a timely way.
In addition to all the excellent thoughts already shared here, I would like to add one more idea: Good Riddance Day. This New Years ritual, which probably originated in Italy, has long been celebrated in Latin America and is now making its way into the US.
The idea is to symbolically destroy the things that you would like to leave in the past. It and include actually smashing or throwing out objects, or writing down the bad things and then shredding, burying, or burning the paper; either way, you are showing yourself and the world that you are letting go of the parts of the past year that were hard for you.
It won't make you forget everything, but it may make things rest easier in your mind. Symbolism can be very powerful, and an act like this reminds us that while the past cannot be changed, the future is still yours to write. It can be a way to begin the healing process.