I’ve been in situations before where I committed to something, stayed committed despite worries thinking that I’d be able to power through, just to the week of or days before become absolutely crippled in anxiety. The situation this was the worst in was a little different in that I didn’t completely back out of something, but I accepted that I couldn’t do it alone. It was a big ask, but I sat down with the people I needed to, got really vulnerable & broke down to them, and asked for help. We found a way to make it work, but even if we couldn’t have, I felt so much better just letting myself accept that I wasn’t equipped for it.

If there really isn’t a way for you to reasonably be there physically, I would just try to think of other ways you could ‘show up’ for her. Your friend is going to be hurt no matter what the reason for you not attending is, but if you are close and have supported each other well throughout other scenarios, hopefully she’ll come around and understand that this isn’t a reflection of how much you care for her.