I haven't posted much here, but I've read alot. Y'all usually give some good advice, so I'm hoping you can help me out. It's a bit of a long story, so thanks in advance for sticking through to the end. Cliff notes at the bottom if you don't feel like reading the whole thing.
Background: I got engaged last November. I have been living with my fiance for almost a year. I had one best friend whom I had been friends with for almost 10 years. A couple of months after I got engaged, we had a bit of a falling out. We have remained friends, but not as close as before- all the issues haven't been quite worked out yet. Said friend got engaged in March, four months after I got engaged. She told me around then that her parents are paying for the wedding completely, and limiting the guest list to exactly 75 people. Since they are paying, they are dictating that she invite all of her family, leaving not much room for friends. As such, she told me back in March that I would be invited, but they would not have room for my fiance and he would not be invited. I told her about the etiquette of the situation, and that I was not comfortable with it. We did not talk about the situation for awhile. She set her wedding date for October 20th 2012.
Fast forward to today. I get a message on Facebook. I'm copying and pasting it here so y'all can read her exact words and not my interpretation of them. Any names are edited for privacy.
Message: "just wanted to let you know that invites are being sent out tomorrow. I lost the battle of the +1's with my mother (her version of mando +1's is outdated) and until we get some "no's" in from the required invitees (ugh) we won't officially be able to invite your fiance. Please don't get mad at me. It was not my decision and since I am not paying for the wedding this is one of the battles I had to lose temporarily. I hope you understand and that you don't get upset when you get the invite and it says "___ of 1" It shouldn't be a problem and there should be room but my mom wouldn't let me send out invites for more than 75 people.

Either way I really would like you there and hope you don't get upset when you see the invite!"
So here's my reaction: I'm hurt that she only used facebook to get this point across to me. She already knew how I felt about the situation. In my mind, something this important and sensitive necesitates more personal contact than a Facebook message. On top of that, I'm just plain offended that she would invite me without my fiance knowing how I feel about it. I almost feel like I'm being manipulated into RSVPing and going by myself. She can't even promise me that there will be room for him, just that there "should" be.
Anywho, I would like to respond to her Facebook message, letting her know how I feel without coming across as rude or offensive. Any suggestions on how to word a reply? And what would y'all do in this situation: RSVP yes, go only if fiance can go, RSVP no out of principial, wait until word that fiance can come to RSVP, etc?
CN: Got engaged in November. Close-ish friend got engaged the following March and immediately informed me that my fiance would not be invited due to budget, etc. Received message today (quoted above) reiterating this, also saying that if there's room and "there should be", fiance can come. Wedding is October 20th of this year. Want to know how y'all would reply to Facebook message and how you would handle the RSVP.
Thanks in advance for y'all's help! Sorry again it's so long. Just wanted to make sure I included ample information.