I’m really hoping y’all have some answers for me, because I’m about done with all this drama and frustration.

Let me start this out by saying that I’ve already had to remove one bridesmaid from my bridal party during this engagement. (She was my college roommate, who had threatened my fiancé when I wasn’t around. She was out the door pretty quickly with that). I replaced her with our best man’s fiancée (we’ll call her Suzy for now). Suzy and I aren’t close friends, but I wanted us to be when I asked her. Since I asked her, she hasn’t been active at all in the activities and whatnot, I’ve had to text her multiple times on several occasions to get straight answers on things, she’s cancelled plans and refused to be with us the night before (we’re staying the night at the venue). On top of all of this, she acts like our wedding is beneath her and is cheap compared to her own (two months after ours). She has just graduated and accepted a job at our local hospital for nursing, and they schedule things two months in advance. I understand that that is out of her control, but my problem is that she will text me and demand dates with absolutely no notice (will give me five or ten minutes to text her with a date, or else she will not attend).
There’s so much crap that has just piled onto each other. I offered her an out about two weeks ago (because I understand she works full time and has her own wedding stuff going on), but she insisted that she still wanted to be in the wedding and got her dress about a week later to show that she did. I guess I just don’t know what to do at this point. This is my fiancés BEST friend/man’s fiancée. If it was anyone else I would’ve probably already told her how I felt and just asked her to bow out. We’ve already had a conversation about stress-levels and how the way she is acting is affecting me, but with her message today demanding more dates before I even have things planned, and threatening to not come to this event too if I don’t give her an answer right away, I’m at my breaking point. I don’t think me asking her to be at those events no matter what is really too much to ask. She’s local, and I haven’t asked her to do anything but attend the events and be there. She’s already cancelled on the bridal shower, the night before, and now probably the bachelorette party. She already has her dress too, and the last thing I want to do is put her out or hurt the relationship between the boys. I just don’t know what to do and any and all advice you can offer would be fantastic.
Am I being overly sensitive or asking too much? How do I deal with a bridesmaid that quite clearly doesn’t have the time or desire to be in my wedding?