If something's troubling you, write it down, put it in an envelope and seal it. Doing so will help bring you psychological closure. Xiuping Li at NUS Business School asked 80 students to write about a recent decision they regretted. Half of them were then told to seal their written recollection in an envelope. Afterwards, the envelope students felt less negative about the event than control students who just handed in their recollection without an envelope. The finding was replicated with forty female students who were asked to write about a strong personal desire that hadn't been satisfied.
Two further experiments shed some light on the process.
via bps-research-digest.blogspot.com