I feel you letter writer. I just ended a 7 year on again, off again relationship. It was the most painful thing I have ever done but he was very manipulative, couldn't commit and had to have everything on his terms. I was always good old reliable, ready to take him back when he felt like it. He didn't even date other people when we were in our off phases (well the last time he ended our sex because he had started dating someone but then that only lasted a week or so and a few weeks later he was already sniffing around seeing if I would be there for him). I've been in therapy and he has been one of the main issues I've been working on. I'm slowly getting better and finding myself again.