Can I decline a bachelorette party invite, and if so, how??

A friend from my former job (Jess) invited me, and 2 other girls from our job, to her bachelorette party next summer. The 4 of us have a group text but don't talk or see each other that often, we really aren't that close. The other girls can't go, so it would be me and Jess' other friends/family I've never met.

I have crippling social anxiety and always end up drinking more than I should to cope with uncomfortable social settings. This would be a 4 day trip, flying to another state, splitting an AirBnb and doing a bunch of activities with virtual strangers. I feel like I'll cause a scene or ruin the vibe by accident because of my anxiety and not having a "safe person" there to help.

Also on principle I sort of hate these intense and expensive bachelorette parties. Technically we could probably afford it, but I ... don't want to? I also just got married and we're saving up for our honeymoon which would be the following month.

I feel bad declining, especially since the other work friends did too, and MAYBE it would be fun? It'll probably be my only chance to do one of these, but I really think I'd be an awkward and anxious mess the whole time.

What should I say to Jess?! Should I make up an excuse about being busy, say I can't afford it, or just be honest about my anxiety??