Hi Mike,
Like the others who have posted here, I would suggest that you not send your ex a final letter telling her how you feel. Believe me when I say that I have considered doing the same thing myself just to bring some kind of "closure" to my relationship. But even though I've composed a final letter to my ex, I've decided that I'll probably never send it to her. The last time I sent my ex an email, I told her that I still cared for her and hoped that eventually she would find it in her heart to give me a chance to do better and show her how much I care for her. Of course I got no response, and after I sent her my last email, I decided that I'd had enough of being slapped in the face with my ex's non-responses and went into no contact mode with her. It's only been three weeks since I started no contact, and already I feel much better. I've gotten past the "pathetic" stage where I was blubbering all the time and wanting my ex to come back. Now I've gotten to the stage where I realize that I really shouldn't be pining for my ex to come back because of the crappy way she's treated me since she dumped me.
Since my ex and I broke up two months ago, I've made every effort to treat her just as nicely as I did when we were together, and it has gotten me nowhere. I didn't lose my cool when she told me she no longer wanted to see me, nor did I resort to name-calling or start hurtling out accusations. Since my ex told me she still wanted to be friends with me after we broke up, I did what I could to be her friend even though I was hurting terribly inside. I continued to send her friendly emails (even though I made the mistake of mentioning our relationship a few times), and even though I initiated 95% of the conversations, I continued to talk to my ex at work in the hopes that we could possibly rebuild what we once had. When it became apparent through my ex's (non) actions (not responding to my emails and not talking to me at work unless I approached her first) that she had no intention of maintaining a friendship with me, I finally decided it was time to go into no contact mode to allow myself to heal. So far it has been one of the best decisions I have ever made. Since I started no contact with my ex, I have been pursuing some of the hobbies I neglected while I was with my ex, as well as going to the gym six days a week. As others here have pointed out, the exercise really helps. Not only does it improve your attitude and outlook on life, it is a tremendous boost to a "dumped" man's self-confidence to notice that the woman on the treadmill next to him is "checking out the goods"!
Since initiating no contact I have changed how I look at the relationship my ex and I had. Although she treated me very well while we together, she has refused to even acknowledge that I was once a part of her life since we broke up. But she still seems to want attention from me, because I know she is reading my emails even though she never responds. My guess is that by now she's probably in a rebound relationship and wants to have attention from me as well as her new boy friend (yeah, another "attention hag"). So, I've gotten to the point where I'm just not going to bother with my ex any more, because I am not going to be the only one making the effort to be a friend, especially since she may be with someone else now. It's just not worth the pain. Sooner or later one has to let pride take over and realize that it's not right to allow the dumper to continue to treat their ex like dirt. As good as I've treated my ex before and after the breakup, I know that I deserve better treatment than I'm getting from her.
One good thing I've discovered in writing a final letter to my ex (but not sending it) is that as time goes by, you can add things to the content which you may have forgotten about while you were grieving over the breakup. For example, I keep coming up with things that I did for my ex while we were together that she seems to have completely forgotten about, like the time I made an effort to loan her money so she could get caught up on her car payments, and the time I tried to find a new TV for her when her old one blew up. When the dumpee starts to remember all that he or she did for their ex before the breakup in light of how the ex has treated the dumpee since the breakup, it sometimes makes the dumpee realize that they are much better off on their own. Your ex's loss will be someone else's gain. Forget about sending her that final letter and move on.