WWID? Avoid the situation. You have changing weather, a fresh horse only 2 weeks back to work that only gets ridden 3 times a week after a long layoff , other horses nearby doing something else and a situation where he is more likely to get overexcited then not. And he’d never been ridden in that field before…,snug contact may have backfired on you too if he is not well schooled to accept it. Don’t forget he was originally trained to run into the bit, don’t know how much schooling he has in yielding to it…he might have thought he was going to be asked to run and confusion lit the freshness/overstimulation fuse.
No no matter what kind of an idiot trainer may or may not be, it’s their job to teach, they probably won’t change what they plan in a lesson for one non lessoning, non owner rider. It was predictable the situation you put yourself in would not result in a successful ride. Not dissing you but…I would expect what happened not be surprised by it. That’s a lot to expect of a fresh, green horse working alone with a crowd nearby. What do you think he learned from that schooling session? They either learn or unlearn every time they are handled. It helps if the horse trusts the rider too…he barely knows you and hasn’t learned to look to you for guidence if scared or excited.
You can assume Trainer is not going to change her lesson plan for you so you need to re-evaluate your program and choices to avoid putting yourself in this type situation where failure is the most likely outcome. Yeah, Trainer should probably have let you know what she was going to ask the class to do but…those taking lessons that are asked to wait or adjust what they want to work on for a non lessoning rider on a green horse often start threads on here complaining about having to do so when they are paying for that time, there’s two sides to that story.
Getting off is sometimes the best option, BTDT, but it is a reward for the horse and if they really get excited, you are not in a great position to control any explosions, you can get knocked down or dragged around trying to hang on to him. And, again, what would that teach him?
Make friends with the lunge line and don’t just chase him around, side reins are a great choice with situations like this. Either you need to get to the barn more days or get someone else to at least lunge days you can’t get there, IMO 3 days a week isn’t going to get an excitable green horse bred to be…energetic…too far. IME it isnt even enough for the less energetic breeds, they may not blow but they often forget new concepts if it’s not schooled every day.
Might be blunt here but this is a typical problem that can be fixed with more thought and better choices aimed at success and not risking failure. Even if you don’t do much, it has to end on a good note…even if it ends early.