A girl i have been working with for the past year is in an open relationship and I dont know what Im doing?

Over a period of a few months I have had a crush on this girl I work with. She told me once that she was in an open relationship and asked what I would do? then said she was kidding. She also later told me they had a deal but no . When I have been drinking with her she flirts with me right in front of her boyfriend and he does nothing to stop it. We have danced Intimately and most recently I have seen her ies(YEAH!)...but we were drinking! This has been happening for a couple months now. Her boyfriend just left for Japan this weekend. I went to his going away party. And the following monday his girlfriend asks me if i would ingest some fungi with her sometime. I said yes All I do is avoid and act cool around her which is starting to seriously eat at me. I wanna tell her that I want her BUT she always brings up her boyfriend at times. I think that this BOYfriend is just security to her but Im at a loss. If anyone would have suggestions or comments please give them. How do I pursue this girl with out seriously ******* up my work and social status? What should I say and do to know for certain she is interested? I just dont have the to find out i was wrong the hard way....okay I just read what I wrote and It wold seem obvious that she wants me but remember she is a girl and girls are ******* crazy!