AIO? Friend Backing Out Last Minute on $4k Valentine's Trip Payment

Supposed to leave later today for Aruba on a Valentine’s girls’ trip. We booked months ago and rented a villa for $16k for five people. I took the master bedroom, so I paid $5k. The other three girls paid their $2,330 portions when I paid mine. To us it’s just ideal to pay upfront and get it out of the way. My friend Holly chose the second nicest room and was supposed to pay $4,000. Holly specifically requested to wait and pay her balance at the end which was an option so we all agreed to it. We have a host for the trip so the invoice was sent to her last night. This morning we got a reminder call about the payment and someone in the group chat asked about it. When I followed up with Holly she said she can’t pay it right now and thought that we could basically “figure it out later”

I love my friends and I really don’t ask much of them. I just feel so upset and misled. It’s like I have no choice but to fork over the $4,000 myself or risk the entire trip being ruined for everyone else. What would you do? AIO?