When my brother asks me to rejoin what should i say?

So my brother is getting married. His finace does not like me, or anyone for that matter. She is extremely rude and nasty to both my mom, and I, also my two year old neice ( my other brothers child). When I first found out my brother was getting married...

he asked me if I would be a groomsgirl, I of course said yes. Then a month later, she told me no, I was to be a jr.bridesmaid. Everyone thought that was weird becuase I will be 17 at the time of the wedding. So I went back to being a groomsgirl. Today I checked out there wedding website only to find that sarah kicked me out of the wedding party, and added my brothers friend in my place. When I called my brother to ask him what the hell happend he swore that neither him nor sarah knew anything about it and it was a misunderstanding. But in order to add the new grooms guy I had to be deleted. I am extremely hurt by this and think that my brother should stand up for what he wants. I have a feeling he will beg me to join the wedding party again. Oh this is the 3rd time she has kicked me out, she is getting more creative each time though . So when my brother asks me to rejoin what should I say?

Say no. Why? You'll just get kicked out and hurt again.. its obvious that he hasn't prevented it the first 3 times, hows the 4th gonna be different? Its obvious that the marraige isn't gonna last, cause she's a peice of crap. So, just look forward to his second wedding.