I'm mad because my sister bailed on my wedding. It's in 2 days and she's the Maid of Honour
Did she tell you why she was bailing on you?
No, I think that she just wanted to be the bride.
It is normal to feel upset when family doesn't want to be in your wedding and cancel plans that they made with you. You can be as upset with her as you want and wait for her to apologize.
I'm going to do something bad at the wedding to show her that she cannot get away with this. I'm going to post a picture of a dick on her facebook page.
That does not seem like a very mature route to take. I get why you are annoyed with her, but you should not stoop down to that level to try to get her back.