NTA don't go.

Please don't go.

You are allowed to say that you're changing your mind about going. Give her back her 25 dollars if it makes you feel better or just don't show up but don't do this if you don't want to. Break your leg if you feel that is the only excuse they will accept.

Never volunteer to be a hostage.

Am having flashbacks of being made to kneel while people harangued me about accepting Jesus as my Lord and savior while I am sobbing in confusion and exhaustion because they had me there for hours miles away from home.

They made me feel I was worthless because I didn't understand exactly what they wanted. They fucking broke me down until I said whatever they wanted to make them leave me alone.

Please don't ever go on a retreat with people you don't know well or trust to some degree.