Dirty_Socks, whatever your real nic is,
I have seen this kind of situation many times in the workplace (too many times personally sad to say and with other co-workers many times as well.)
What you have here is the Office Attention-Wh0re. She is just playing you for attention, showing off / marking her territory for the other co-workers, getting what she needs 24 hours a day(you're just the work-hours attention-giver).
It is as classic as it gets (everything from the sexual innuendu, to the jumping up in your lap when the other female co-worker comes in.)
Back-off totally for about a week and watch her attach herself to another guy in the office / restaurant / whereever you work.
Office Attention-Wh0res do sometimes cheat with you but it always ends up in a really bad situation eventually.
And, by the way, everyone you work with knows what's going on and the smarter ones (especially the women) recognize that you are getting totally played.