Someday you will ache like I ache

There is a report to go with today. But I don't know how to describe it. I'll do my best.
My usual co-worker is on vacation this week. I'm doomed to work with someone that I cannot stand. She's ineffectual. I could sling a lot of insults her way, but the gist is that she is very bad at the necessary skills of the job. She refers to me as "the temp" or "the girl from Randstad." I have no name, no identity, nothing. But she's fine with letting me do the work. Deal with the public, pull the holds, answer the phones, etc. while she sat at the back desk and ignored the screaming children, fights, insults and other issues of public library life. I told her no fewer than thrice that I would take my lunch at three. That I take my lunch at three every Thursday. When the head of the branches came to relieve the Ineffectual One for lunch this exchange occured:
Branch Head(standing no greater than 3 feet away from me): When does she take her lunch?
Ineffectual One: I don't know. She hasn't said.
Me: Three. I said three.
BH: Well, I can't run the branch alone.
Me (under my breath): Funny, I did it. And I'm just a temp.
IO: I can't take my lunch until you're here. She should've gone earlier.
Me (carrying on the tradition of ignoring everyone else in the room and talking to the air): I'm going to lunch. Be back at 4.
BH and IO (Watch me pick up my stuff but say nothing. Talking to temps is below them.)

I ate my lunch in my truck. When I was done eating, I went for a walk. BH made the shelver stay and do the work even though her shift was over at three. Worthless twat. Not the shelver, she's a bystander.

That's not the interesting part. I don't know if I want to talk about the interesting part.

Suffice to say it made me want to hurt myself. Bad. If I hurt myself I probably won't try to hurt the person that I really want to harm. And I want to hurt her. I want to cut out her tongue and shove it down her throat until she gags on her own words. I want to beat her until there's nothing but a bloody pulp left. I want to cut off her air until she can't even beg for mercy. I want her physical pain to come close to what I'm feeling emotionally right now.

I'd never hurt anyone but myself. And then only enough to distract myself from the anger. I'm not suicidal. Don't call the cops or anything. I'm thinking a broken hand, a good swift punch to a wall. Then I can work, but I can't actually do any of the tasks I'm suppsed to.

Yes, it's that bad.