To be happy, you will need to acknowledge the your feelings, process them, and move on to the next stage of your life. [substeps] In your letter, you might write about how the friendship started off great, but then went downhill.
[header] How to deal with an ex best friend [title] Find closure. [step] When your friendship ends, it is important that you accept that and resolve your feelings. You can write a letter to your friend expressing all of your feelings (you don't have to send it to them), or you can create a ritual to symbolize the end of the friendship.