Girl in an open relationship seeking me out?

Over a period of a few months I have had a crush on this girl I work with. When I first met her she was moving out of her boyfriends apartment for more personal space. She also told me she told him in her sleep he had a small . She then later told me that she was in an open relationship and asked what I would do? i was so thrown off i made a stupid comment. then she said she was kidding. She also later told me they had a deal but no but she would be ok with him having . 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! I have had the opportunity to kiss her but we were drunk and honestly i was scared. This has been happening for a couple months now. Her boyfriend just left for Japan this weekend for 4 months. He is a very nice guy and is never mean except when i went to his going away party. he made some seriously absurd comments. But I took it because I had it coming. And the following monday after he left his girlfriend asks me if i would ingest some fungi with her sometime. I know she has only ever done that with her boyfriend. 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 brings up her boyfriend at times which is strange. 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 don't 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! What should I do with out being to forward?