Your game here is to make her fear what YOU will do.
Meaning - when the cat is away the mouse will play.
Now - this is not something that you can cultivate over a few days - this is what you must create from day 1.
You have failed to do this, because she would go to the bachelorette party without thinking of what YOU will do.
If she does not question what your plans are - then she has upper hand over you.
You cannot live your life speculating on what she will or will not do - see? is that a life you want?
Your life should be based on what YOU want to do - and how you feel... not her.
Your attitude above all else should be superior. You ARE the life and soul of the party - whatever the circustance - life around you, is better than life around anyone else. Once you loose this, you loose her - and slowly she will leak away from you - and want to spend time elsewhere.
If she goes - you should plan with your peeps a night of fun, drinks, and women. Do not call her. Do not think of her. And worry not.