This is why it isn't a good idea to date coworkers or anyone within your social circle, way too much drama. Consider this, if she rejected you early on in a normal manner you should be able to continue on with your life. Where the issue lies is when these women lead guys on, flirt with them, etc. with no real plan on going out with him. This is how a lot of women act today, as many are addicted to attention, and the consequences down the road are not pretty.
Now, even if you did in fact go out with this woman, perhaps more than once, it is far more likely for it not to work in the long run. In situations like this you can never go truly back to the way things were because there is emotional investment, pain, etc. I personally feel that if you are going to meet women in a context like this, or something similar, it is better to get to know them over time slowly and not rush into things. The problem with this though is that without expressing interest you could essentially friend zone yourself, which is the reason why I think it is better to just forgo on this all together.
I don't like drama, having my time wasted and people using me for their own gain.....so my natural inclination is to avoid this.