i think i'm just.... done

I've only ever had to write off one good friend in my lifetime.
We were friends for twelve years... the important years too... through all of jr high, high school and after.
Long story short, there was an occasion where I learned I couldn't trust her with my friendship anymore. I learned she had spent the latest five years of our friendship judging me, jumping to conclusions, and completely assuming the worst of me and my life. Not aloud to me of course; until a certain evening when she decided to get it all off her chest. We had a huge drawn out heart to heart, and at the end we were crying and hugging and saying things would be better between us because of it... but I knew they wouldn't. They couldn't be, knowing the way she thought of me. It changed our friendship and slowly it just didn't exist anymore. She wounded me too badly.
That was really sad for me. I missed her often. Five years later, we reconnected and were slowly able to be friends again, but that real closeness will never be back. That trust, that unconditional love.

I find myself wondering if I'm at that crossroads again with another friend.
I hate this feeling.
C and I have only been friends for not quite three years. She was a great friend to me when I needed one... we hit if off right away and had a ton in common. Sometimes it was weird how alike we were. Great friends.
But over the past year or so, I've started feeling like things are off. This has turned into a long distance friendship now, and I admit I'm not the best at those. I'm not a phone person, but luckily we kept in touch very well online. I think that's part of the problem. There have been a couple of instances where we've had misunderstandings... (mostly her reading me wrong or again- jumping to conclusions) but we've worked through them. However, at the same time, I know from experience -she OFTEN vented to me about other friends- that I might not know the whole story, what she really is thinking, or if anything is even wrong to begin with. Maybe I'm paranoid, because this is all long distance and I'm not there to see how she really is, but I end up always wondering if I said or did something wrong. Like she's bothered that I don't call her, that I'm not keeping in touch enough, or that I said something wrong, or that she's taken something I've said out of context and blown it up out of proportion (which has been done a few times). Like I said, it's probably mostly in my head... but still it's there. It's there because I've seen her do that with other friends. It's there because she's denied there was anything we needed to talk about in an instance when I knew for a fact that she had a big issue with me. It's there because I know she's talked to other friends about issues she had with me, before even talking to me about them.

I really hate that feeling. I want to be there for her, I want to be easy friends. But I hate that when I get an iffy comment (or lack of response) from her, I always start imagining the worst. I hate that I feel like an insecure immature girlfriend... "are you mad at me??", but I hate that I can't completely trust her enough to not ask and not wonder if something is going on that she's stewing over or talking negatively with me about with someone else.

I'm really almost ready to walk away.
And I hate that feeling too.
On one hand, I feel like what's the big deal?... we haven't been friends forever, we're not a part of each other's regular life anymore, we really don't talk much anymore at all, what's the big deal if I just say I don't want to deal with it anymore?
But at the same time, she's one of my friends. There was a friendship there. It is so hard to just say good bye to that. To say that you don't care anymore. Because it's not true.

I just don't know what to do.