Holy shit. I really, really don't know what to say to that. That must've been terrifying.
To be fair? Your story, totally terrifying as well. One time my brother convinced me to rub poison ivy all over myself so I would get off school. I remember intently searching out all shiny three leaved (leafed?) plants I could find in our wooded backyard. I truly rubbed them everywhere. I had to go to the hospital because my face swelled so much my eyes were nearly shut. They put me on steroids and that was when I finally learned to swallow pills. I think I was in 5th grade. That would be about 9 years old, mabe 10 as it was the end of the school year. That seems less "yes that really happened" than just "this is a crazy fucked up story" though. As I responded to this thread I noticed more of my stories are the latter than what i think the former describes.
Regarding terrifying - I think I find your story so terrifying because my panic response is - for various reasons - to just shut down and become uncomfortably compliant. I will basically do what someone tells me to, even if it's something I really don't want to do. I think you understand why this can be problematic. I try to avoid all and any situations where that could happen and I've been successful/ish so far.
I feel you on the "this is a crazy fucked up story" part. I've had many incidents where I'm like "I'll tell you a funny story" and listeners are like "That's fucked up".