Is this relationship worth it?

I have been with a girl for around 1 year and our relationship has gotten very tense lately. The main problem is that we misunderstand each other alot, and that leads to lots of arguments. She drives me insane, and (according to her) I drive her insane as well. We can have good, fun and intimate times together, but I feel that she is ruining my health with her stubborn and crude attitude, because as angry as that makes me, I can feel the symptoms of the anger in my body. She demands a lots of attention and when I fail to give her that, she tends to drive me nuts.

That is the dilemma, where I compare the good sides about this relationship with the bad ones. The bad ones are the highest, in my point of view.

She makes me feel so sad and angry sometimes with the way she speaks to me, that I end up calling her very bad words. That way I (subconsciously) transfer the sadness and anger back to her, and that way it just ping-pongs back and forth.

And as wrong as it is, I actually slapped her for a week ago, because she was really frustrating me with the way she spoke to me, and at that time I felt helpless and like I didn't want to down to her level. I feel bad about it, but it felt good when I did it, because of the way she spoke to me, and how it made me feel - and that felt like justice. Yes I am an idiot for slapping a woman, but that is the first time I did it, and that was after very long time after putting up with her behaviour.

Many times she tends to ruin my day, when I call her with good intentions and suddenly she brings some old grudge up, and tries to analyze: it, me, and why I act the way I do.

I would like to move on with my life, without her, but I know that with her obsession about; trying to understand everything, that is not going to be easy. She is over-sensetive/hysterical, and succeeds many times in making me feel bad about how she feels herself.

I am a person that absorbs alot of the mood, that I am surrounded by, and therefore you can see how easy it is for me to change moods. To rephrase: The mood smears out on me very easy and my short is rather fuse when it comes to anger.

EDIT: (updating)

I'm not real sure what you're asking here. Clearly you two need to go your separate ways. You know that. So what's the problem?

Just move on buddy, just move on. Otherwise, you'll go into your grave pretty fast thanks to so much tension and depression.

I am asking how I should make a clean break. Should I just ignore all her messages, mails, calls, etc?

No, Aleque, that's disgusting. Ball up and break up with her, face to face.

I can't believe you slapped her, you asshole. You seem to have a combination of no spine and no self-control.

I tried breaking up. It's not that simple, especially when we threaten each other so much with breaking up.

Then write her a goodbye letter, hand it to her in person and THEN start blocking her. Don't just disappear.

Break up with her in person. You've been with her for a year, you at least owe her that. Tell her you're relationship is toxic, you need to move on from it, and you need to cut contact with her in order to make a clean break.

You're lucky she didn't call the cops on you for hitting her. I'd work on your anger management if I were you. Physical violence is a cowardly and childish way to deal with people in your life, especially ones you supposedly care about.