Lost a girl twice, need help

So, I have this problem and I'm starting to lose my mind. I started dating this girl everything was going great for a while didnt get into a relationship though, she didnt want to yet. Eventually I screwed up because I unfortunately started to smother her. She really pissed and we stopped talking for a while and I thought it was over even as friends. About a month and a half later we started talking again and she decided to give me another chance so apparently she actually did see something in me. Things seemed better than they were the first time and I was insanely happy. Then because of my awesomeness /sarcastic, I unfortunately was beginning to smother her again and she ended up telling me that it wasnt going to work out anymore because of it but we could still talk and be friends. I was crushed and heartbroken because words cant even describe how much I like that girl. I decided to write her a letter apologizing and saying how i feel about her and how much i wanted to make something work. She didnt like that and said I couldnt handle talking to her anymore because I might get the wrong idea and that she doesnt think that we should be friends anymore. What has me confused is we work together and at work she is nice to me and acts like nothings wrong but thats the only place she talks to me now and she still has me on her facebook/myspace/IM so she still leaves me ways to contact/talk to her. I don't know what shes thinking and what her intentions are, you know if she still sees us being friends sometime in the future or maybe even try dating again. I don't want to lose this girl out of my life even it means just being friends with her. Should I just not talk to her for a while and give her some space, I just need some help, my heads been spinning for the last week.

She has a duty to fulfill at work, and that is to maintain a level of professionalism. Being courteous to fellow coworkers for most people is necessary.

And as for leaving you on her friends list on various networking sites, well, it sounds like she has a level of maturity that doesn't include knee jerk reactions (in the form of deleting you) when something doesn't pan out.

She seems more logical than you. Leave her alone.