Officially Back-Stabbed

So I was kind of happy this week, despite all my conplaining and teeth grinding and worrying. I was happy because I was making friends in lab. We were hanging out and most people seemed to like me so far.... this was something I had not been able to work on during the semester because of the time constraints.

I am going to start this story from the beginning. A few weeks ago, "Lab girl" pointed out to me that I was not scheduled to present infront of the institute (there are these weekly meetings that the institute holds and some miserable student or post doc presents and gets asked questions as if it were their Qual). I told her not to tell the administration anything because I had to teach this semester and I had just started looking for a new project. She told me that she was going to say it any ways. I thought she was kidding but I warned her not to say anything.
All the sudden Today Lab girl comes to me and tells me that she told them that I was not presenting. And that now I had to take 1/2 her time at presenting.
So here I am. I have no project. I am exhausted. People are trying to push me out of the project that I have kille my self for. I have to teach some spoil stupid brats some immunology and I have to somehow prepare for my Quals.

It is not the fact that I have to do the presentation that depresses me. It is the fact that I got back stabbed and now. Well now I have to spend energy avoiding the fuck out of this hook worm (the person I am refering to as lab girl)....
Why? Why do people think it is okay to piss me off? Why? Why in the world do they look for my fury?