Thanks for the advice all.
1. Yes, now that I thought she was a trustworthy friend I have said things that could be very problematic. It doesn't help that she is the type that exaggerates anything I say. It was stuff like a mutual friend was fired instead of voluntarily relinquishing her position (but still works there). Or any gripe I have mentioned about my boss. ( I suspect strongly she says these things to other people now but is less inflammatory and vindictive than she would be otherwise).
2. I like the idea of inviting other people but we don't really eat lunch together, just go to the cafeteria and return to our desks. She is also very jealous with response to new people. Also, honestly, most everyone around us are so toxic I wouldn't want them to be friends anyway.
3. No matter what I will not be able to rinse her out of my life. We have offices next to each other in a place that doesn't have many other offices. So if i run to the printer or the bathroom ... she is there. Plus, the fact that we are supposed to (and have to) work together.
I need to find a way to discourage her. I used to have another toxic friend but I lost her due to this friend. (blurg)