Bridesmaid Stormed Out of the Batchlorette Party After i Called Her Out For Treating Me Like Crap

My name is Megan and this past weekend we all (4 bridesmaids, 1 MoB) went to Breckenridge Colorado from Denver for my batchlorette party.


One of my bridemaids Elle (my fiancé cousin) had booked the airbnb we stayed at because she is very well off and can pay up front for the place. The bridesmaids all went on a zoom call and booked this beautiful cabin that sleeps 12. Because of this I was able to invite my grandma and aunts to join us and I was so excited about that. (My grandma and aunts didn't end up being able to make it, thank god).
As we all drove from Denver to Breckenridge Elle wouldn't give us the address and really wanted us to all follow her. As we pulled up everyone but Elle was surprised that it wasn't the cabin they had discussed and booked over zoom but it was a condo that slept 6 (good thing my grandma and aunt didn't show up). There were two rooms one the slept 2 in a queen bed and the other room slept 4 in a full bed and bunck beds. My MoH said this isn't the place we booked and Elle snapped at her and this is when I could feel Elle wasn't acting right.
Everyone but Elle said I could sleep in the master bed with my MoH and that made me feel special. We moved our stuff into that room and started getting settled. Elle was clearly uncomfortable and started saying "guys we need to figure out the sleeping arrangements" but everyone agreed as the bride I could have the master. Elle went up to me and told me she needed the master so in the morning she could do her homework and that the mater had an outlet for her (weird excuse as all rooms had outlets)...I was so caught off guard and under pressure I just said okay. I know I should have stuck up for myself but I was so taken back. So awkwardly while Elle was happily moving her stuff to the master room and and started getting ready I moved my stuff out. It felt so wrong, I was sad and did not feel special.
After that Elle was happy but throughout the night she was mocking me saying "whatever YOU want" "It's all about the BRIDE" but in the same breath Elle was so set on doing what she wanted to do and set on going to this restaurant she wanted to go to but no one else wanted to. I compromised and said okay let's just order it here and stay in and she got so upset and started complaining that the delivery fee would be too expensive and not worth it and that we had to go into the restaurant. We all just compiled and went out but luckily the restaurant she wanted was closed so we all chose one that we liked and it turned out great.
We could all tell that Elle didn't want to be there. She was talking about leaving early and taking my out of town bridesmaid with her (when my out of town bridesmaid told me she didn't want to leave early). Elle complained about her homework and how she had to use the master room it do her homework in the mornings and she wouldn't be able to do other activities in the day time with us because if this homework issue. (She's been talking about this same homework since the bridal shower 2 weeks ago and thats why Elle couldn't participate in the shower) two weeks is long enough to write an 8 page paper...but whatever..
The next morning she didn't do her homework and she left to go get coffee and go to the art festival with us. It made me mad that she was being so dramatic about needing the master to do her homework and that's why she couldn't hangout but never ended up doing her homework. I called her out and told her how the girls and I were feeling. How it seemed she didn't want to be there. How she kicked me out of the master room and it didn't make me feel special, mocking me wasn't nice, and how the place she booked wasn't even the place talked about and how thank God my other family didn't go. She mentioned that no one paid her for the place but I corrected her because some of the girls did and my mom paid. She stormed off called her mom (my FH's aunt) and talked bad about me. We could hear her on the balcony saying "wouldn't it be funny if I went to the Batchelor party instead! Hahaha".
She left called my fiancé and went to his batchlor party that was in Denver..I was pissed that she involved him at all and that she went to his party!! Later my fiancé told me that if I called him and told him the full story he wouldn't have allowed her to go.
She is now asking all the girls to pay her double what was agree upon and they originally calculated the cost of it being the cabin that fit 12 ppl and not the condo. We tried to reach out to the airbnb owner and she won't send us the receipt as we aren't the ones that booked it. We looked up the going price, fees, and taxes and its hundreds of dollars cheaper then what she is saying but we have no way of fully confirming the real price.
At this point I need to talk to her as she is my fiancé cousin and we have some family events coming up involving her. What should I do and what do I say to her? I don't believe I need to say sorry for anything. We all agree when I brought it up to her she was gaslighting me. I'm so hurt and shocked she even acted like this as it wasn't like her. I know she talked bad about me to my fiancé family so it will be awkward seeing them going forward because I don't know what truths she told them.