Hi. I live and work in Italy for just over a year now. I work in a small office (there are 6 people in the same room as me and then about 15 others).
Anyways, I met a guy from another department a year ago, and we basically fell in love and moved in together last september (i know it was quick

, about the same time he moved to a new job.
The problem is with this girl at work. She basically sits in front of me, and is in love with my boyfriend. She had got together with him twice (as in 2 nights) in the period of 2 years when he had had a few 2 many drinks and for some strange reason she actually thought they were going to get into a relationship.
Anyway, since we got together she has been a nightmare. She started by pretending to be my friend at the beginning and asking me about our relationship (then e-mailing my man and telling him I was a right b**ch because I would go up to her to rub it in on purpose).
She then got involved with my boyfriend's colleague (and friend), actually came on a weekend away with us (slept with him!) and then wrote a really angry e-mail to my boyfriend saying how she had done it just to make him jealous so why wasn't he?
Then, she started following me and copying me; she started coming to my gym at the same times as me, going around with a 2 litre bottle of water (as I always have done), dying her hair light brown (it was sort of dark red before), she stopped wearing makeup, picking up the phone in english, she even bought a moped 2 weeks after me (but had to return because she was too afraid to drive it).
Lately it's been the worse - she has started bad-mouthing me to my colleagues, and to my boyfriend when he calls. She is completely obsessed with what I do, tells people I always leave early, that I fake doctor's notes, that I never go for lunch with them. I don't work on projects her, so why should my actions at work affect her? (besides the fact that she lies about it all).
I finally confronted her at the gym (not easy to do in a foreign language), but it made no difference, except that I resent her even more now. She's not a very bright girl, and it all seems to have gone in one ear and out the other. I don't know what to do, I must seem like the nasty one to the other people in the office because I don't fake being nice to her. She's also been here 3 years and I've only been here one year (I'm 25 y.o. she's 28/29). I like all my other workmates, they are all young and hardworking, but I'm actually thinking about leaving my job now because I can't handle being around her all day. Any advice?