We started off as fairly good friends, she was open and polite. But as time went on i discovered she has this sensational amount of hatred i have ever experience for people. I would be positive and encouraging, trying to lift her spirits up, when she has had a hard day. But i soon discovered she took offence over little things as time progressed; the way in which someone looked at her, giving her a compliment, or making a light hearted joke.

Now i know, i am no saint, but everyone in my department knows, i'm a bit of joker. And the things i say are crazy and mind shocking but they know its a joke. When tiring to have a serious conversation about contracts with her, i said there is a phrase in the contract that is ridiculous, and gave a ridiculous example to go with it, that was not directed at her. She then only focused on that ridiculous example and neglected the the rest of the content of our conversation. Getting upset over it.

I apologised, but she is acting like a moody teenager (it doesn't help, she is one). And now is refusing to go in the same room as me, to talk to other work colleagues. To talk to my team, she instant messages them telling them how bored or angry she is. During a conversation with a female colleague she would follow her because she is lonely, then listen into the conversation and burst out with profanity to state her objections of what i said. She threw a pen at me and actively segregating me, turning my own team against me. What arrogates me the most is i find out a member of my team apologises on my behalf for making things awkward behind my back.
It feels like she has a vendetta to actively crush me, and pushing all my buttons until i flip out. (note this has been going on for a month now) I can't believe, i am petrified of a child.

How to deal with a moody teenager??
Do i keep cool and calm and let this wash over me???
Does it sound like she wants to get a reaction out of me, especially when i have been sincere and polite after apologising??
Do i take this further to management, especially when she almost got my supervisor sacked for her childish behaviour, because of telling tall tales that others then reported??
What would you do???

Thank you for taking the time to read this.