I also do not know how to respond to this, I suspect you really wanted to 'let it all out' though and that's perfectly ok, better out than in. This was a long letter and it sounds like you've put a lot of thought and careful consideration into what it said.

A lot of times you have to be out of the relationship and looking back at it from the outside before you truly understand what was going on.

I'm sorry to hear that she made light of your private gestures of love by wearing your collar as part of a costume in public and also that she was always so oblivious to how you wanted to keep that part of your life private.

I'm also sorry that you didn't seem to have a good experience with fetlife, my local community are all on fetlife and we seem to place the most updates about the local events and play parties more often on that site than on the official website (seriously, the official website practically never gets updated)