If you really love a person, you will continue to do so even when it's over. I broke up with my ex 3 years ago and I still miss her sometimes, even though the way our 5 year relationship ended was a mess. She ended up leaving me for my friend. Betrayed by two people at the same was something that I can pervertedly appreciate now, because I hit rock bottom and got through it without doing anything stupid, like starting to smoke again. Although the whole process fcked up my studies for that year, I stopped going to classes, and eventually it lead to me doing some soul searching and I quit my IT-studies. I wanted a fresh start and so I applied to a university in another city to study social economics and here I am now.
I went through the classic five steps of grief: denial, anger, bargaining, depression and acceptance. And eventhough I got through the acceptance, I still got jealous for her dating other people (after my "friend" dumbed her). At some point I had a fck buddy thing going on with her and she even asked me back year and a half ago, but I told her it wouldn't work out. Couple of months later she started to date another friend of mine (shows a lack of imagination). And I haven't spoken to her or my "friend" for over a year now. Even though it had been 2 years and I had rejected her, it still felt really bad, especially because the guy used to be a really good friend of mine and I had just been spending time with him on his summer cottage drinking beer etc. and in the meantime he was dating her behind my back. When I found out and confronted him and asked, why he didn't tell me sooner, he told me that he wanted to first see, if it would work out between them, meaning that had it not worked out, he'd never told me. This is the reason I won't prolly ever forgive that backstabbing bastard. At least my other friend felt really bad for what he had done and had so big moral issues that it lead to him leaving my ex.
We used to be close even after we broke up, so severing our contact still eats me sometimes. Last time we spoke I said something nasty, I don't exactly remember what it was, because I was so angry then, but I think I threatened to sleep with her mother and/or sister so she'd know what I felt. Of course I would never do it, first because here mothers fugly and secondly because I won't lower myself to her level. I think I also told her not to call me ever again, because I felt that the only times she called me were when she needed something from me. I think you are also in the danger of getting exploited, she knows you still love her and takes advantage of it, and I'm not talking just money here.
Couple of weeks ago I wrote a letter to my ex, where I would have apologised for the things I said to her last time we spoke. I sent it to her email, but her email account had expired. I was kind of expecting it and I didn't mind it, because I also decided not to send it to her in snail mail. It's like you said, sometimes it just feels better to write things down. I have decided not to be the first one to break the silence. I know that deep inside she still cares for me, so in a way my silence is a punishment for stealing my friends. I blame the guys too, for thinking with their dicks. Their punishment has also been pretty bad, because they lost their face and in the eyes of my friends. They got "excommunicated" and are no longer in our little circle of trust.
It doens't really matter what you choose to do now, because at some point you will regret the decision anyway. But if I were you, I would do a clean break. Atm you are just hurting yourself when you hang on to her, and you can't move on. There will come a time when you wish you had done things differently, but eventually you will feel better, and I'm not going to lie to you, it could take some time, maybe even years, but eventually... It took me three years to become ready to date again. I shut myself, because I felt that I would have so serious trust issues, that I wouldn't just end up hurting that other person. And not to fool myself, I'm pretty confident, that my trust issues are probably going to ruin my next relationship. But I just have to live with it.
I'm happy for having gone through all of it. Had I not gone through it all, I would probably be an unhappy engineer and a dick. I am now much better person then I used to be. And although I lost my trust in people and some of my selfconfidence, I have found inner strength in knowing that there's nothing that could bring me down anymore. Nothing can throw me away from balance.
My best luck to you.