Not sure if you're a religious man but even if not, this lesson is Universal:

God clipped Satan's wings and tossed him to hell because Satan was being a pain in the ass. God didn't send Satan to Hell because he hates him. . . no, God still loves Satan. God just doesn't want to deal with him or save up his Saturday nights to play poker with him. God doesn't cut Satan off. . . in fact, it's the other way around . . .

On the other hand, what you did to this girl is more in line with what Satan likes to do. He befriends those who do him favors and those who don't . . . well, he likes plays the role of a disgruntled 5 year old.

What I am suggesting you to do is what you should have done in the first place. Whether it's because you realized she's a pain in the ass or whether it was because she wasn't sucking your cock, you should have just allowed her to stay in her little hell and let it all go. "I'm not contacting you and you're not contacting me." - What kind of language is that for a grown man?

Let her contact you any way she likes . . .if she nags and goes on and on and on, you need to learn to say, "Hey, I'm sorry, I was just in the middle of something. Is there anything I can do for you?" - Silence. It's OK to change subjects. It's OK to tell people that the conversation topic is depressing. It's OK to speak your mind. Do you know what happens to pain in the asses who lose people to shit on? They usually fuck off to find a better toilet. It will be her who chooses to stay in her shit hole. But look at what you're doing here . . . at least you're giving her a shot.
You're an interesting guy . . . your choice of words. . .

SHE has issues? Have you ever met anybody with issues who do not PROJECT their issues onto others? What you're saying is that she's a pain in the ass. And you used a 'sad' face. You must find some comfort in sadness . . .

Most people who 'discover' that their mates are a pain in the ass:

1. Shit!
2. Figure out how to dump her nicely.

Life's too short brother.

I think I see what you're getting at here. I suppose I just need to come to terms with the fact that the girl I always thought I could find just doesn't exist. They're all pain in the asses and should be treated as such. And when I finally meet one that is willing to sacrifice for me, maybe that will be one that I invest into, rather than me always giving up everything for them and then acting like a disgruntled 5 year old when it doesn't work out for me.

I'll write her back with a letter as you suggested...and then not be a door mat if she decides to pursue further contact.