It's taken me a day or so to get together my thoughts but I think I'm about ready to try putting them into words.
At first I was shocked and then angry and then just terrified. Now I'm beginning to accept it with a sad sense of the inevitable - let's be honest, we both knew it wasn't going to last. Despite what you might think, it's not that I felt I could do better. I loved it while it lasted, although maybe I didn't always show it. And in reality it wasn't you - it was me. I was just not going to be the person you wanted me to be. I tried, maybe I could have tried harder. But you shouldn't have to put up with me and my problems out of a misplaced sense of loyalty, or worse, pity. And you helped me a great deal, but you shouldn't have to wait the years it could take me to improve. You need someone right for you, now. You deserve that.
I wish I'd done things differently, but still, I'm trying not to blame myself too much. Wallowing in self-pity or worse, regressing to how I was before, would do me no good and I intend to take this opportunity to regroup and learn and maybe even figure out what it is I really want from life. Things move on, there'll be other chances, and maybe one day I'll find "the one".
I just want you to know I'm sorry it didn't work out, and I don't blame you for giving me the boot. I hope you can forgive me my faults, and there will be no hard feelings between us. I promise this is the last you'll hear from me, unless I desperately need a reference of course.
So goodbye job, it was nice knowing you.