Why is she like this and what can I do about it

[Hooo!]

i dont see the problem

either you want to do things with and/or for her
or you dont

i dont get what the problem is?

If you dont want her to contact you in any way then tell her and block her and ignore the **** out of her - or file a harassmant order if she keeps stalking you
If you do want her (pun intended)
then do it and live with the consequenses

i dont get what this is all about. But i didnt read the whole thing properly - so maybe ive missed something.

[TheEvilJester]

I think the problem is that he HAS gone out of his way to tell her to buzz off and she refuses to stop anyway. So he HAS already gone the route of telling her to leave him alone, but to no avail. So, I do agree with you (and said as much myself) that the approach may need to begin to become more and more firm if she doesn't take the hint. Which may well need to include a harassment report filed at work against her. Hopefully it doesn't escalate to that degree, but better to tell your side of the story first before she gets a bug up her butt and decides she's going to file a report on YOU and make it look like you are the one who has been inappropriate.

[Hooo!]

if that is really the case and the girl doesnt bug off
id go with
"Listen Lady. I do not like you and i never have. Its not that I hate you or anything. I just dont care about you. I do not want to have any contact with you more then neccessary. Stop contacting me for good. Stop annoying me or whatever it is you are doing. I do not care. Leave me alone."
And have people to back that up.
The important thing is to really have people who see you be non agressive but direct. Id also contact my lawyer just in case something goes to bonkers.
I dont really think this topic is love related tho. I rather think this falls under harassment or mobbing or the like. And since that is a law relevant topic Id really talk to my lawyer about it.

[noreenlee]

You can surreptitiously double cross her. After about 8 months she will step in it. I tried to list steps but system said I was logged out. Is there a timer?

Basically gently lead her on to her face while gently despising her behind her back. Eventually through her overhearing something or eventually through her learning of your secret gf...She will make a fool of herself as well as lose social credibility.

But be gentle and subtle. The rich reward in her transformation and subsequent growth is worth patience as the chism grows between her perception and your actual reality. Also be gentle because in the end, she will be more "real" and who knows what that could lead to. So retain "plausibility" that you never hated her, that the microexpressions of secret disdain behind her back were just because you were having a rough day. Done correctly, she should never know of them, not know of any very subtle, non-committal gossip against her, or disapproval of girls who flirt behind their bf's back.