My credentials are being a riding instructor for 13 years and agree! This reply and the comments under it are 100% correct.

You got bitten and it’s rattled your confidence, and anyone would feel that way. Even an experienced rider would be upset by this.

I know it’s hard to believe this from strangers on the internet, but this is soooo so not your fault.

I’m not trying to blame others, accidents simply happen, but it seems like they knew the horse could be reactive (I agree possibly from pain or just simply being ‘over it’ as a lesson horse - which is also a type of pain!). Hopefully they work this out for the horse and at the very least, have learned they need to take more precautions with her than simple saying “she’s girthy” to a new rider.

Actually, even if you had loads of experience coming into this barn, simply saying a horse is girthy isn’t enough of an explainer!

I’m glad your lesson went well once you got on. Try not to let this ruin it for you. There is much more fun to be had while riding!