Who’s In The Wrong?

Long post. I’m at a loss and don’t know how to do anything right without making people angry.

My wedding is going to take place about two hours away from where most of us live.My mom wanted to block a hotel that I was initially ok with. However, the manager was incompetent. She NEVER replied to any of my emails or phone calls (I only had generic questions). I was very frustrated and told my mom it wasn’t worth it and to forget about them. Two months later, the manager sends a contract. I told my mom she can do whatever she wants, but I’m not staying there due to their poor management. My mom signs the contract anyway with some notes requesting some changes. The manager never replied back. My mom had signed this in October (or November, I don’t remember). I repeated myself to my mom that I’m not staying at the hotel, but this is her choice. It’s now January and I’ve asked my FMIL to block a hotel because this is stressing me out and my mom is fixated on the one hotel she picked. I found a hotel I liked, asked FMIL to visit the site and block it if she thinks it’s good. She looked it over and helped me block 10 rooms. I told my mom what we were up to and she said she would see about canceling the block from the first hotel. Sounds normal, right? Instead, the manager talked her into keeping the block and claimed she never received the contract (I think she is either a lier or incompetent because she never replied to my emails or called me back).
Whatever. I’m flexible and it’s a courtesy block and it isn’t going to cost her money if the rooms don’t get 100% occupied. It also doesn’t matter to me if we have more than one hotel blocked. My mom texted me the info about the block. I replied that it’s fine, but I’m still not staying in the hotel as I have stated several times before. Coincidentally, I’m at my FMIL’s home at this time. My mom calls me and asks questions about the new hotel and why my FMIL was in the town to make the block. I’m honest with my answers and that it was convenient for FMIL because she needed to exchange a shirt anyway while she was there. She’s asking me questions that my FMIL can best answer so I give the phone to her and put it on speaker.
My mom blows up at FMIL and is angry that she took her job, I spend all my time with my fiancé’s family (true, but there’s a few reasons for that I won’t go into). My poor FMIL is now in customer service mode trying to reassure her that my mom is important. I haven’t spoken to my mom since this incident last week.
My FMIL calls me today with a compromise. We book one of the special rooms at my mom’s hotel as the getting ready room and I’ll still sleep at my hotel. I admit my mom’s hotel is more pretty on the outside and would be more picturesque than the other hotel. However, I can’t think straight and it bothers me that my FMIL partly wants to do this because she doesn’t want to ruin my relationship with my mom. It’s not her fault and I almost cut my mom out of my life last year. My fiancé thinks we should go with this plan for now. Whatever. I’ll go with it, but I also think this is getting ridiculous.
I’m tired of this drama. I’m half ready to disinvite my mom but it would probably also mean cutting off other members of my family which doesn’t seem fair. The other thought is to cancel the wedding and elope, but it seems cruel to cancel a major event in my life because of one person. I’ll pretend I don’t care about the deposits that I won’t get back if I go in this direction. Obviously I can’t fix past mistakes, but I don’t know where to go from here at this point. What would you do?