Tread very carefully in this situation. I'd start out with what you've already done by saying no to the horse leaving the property. Then I'd reach out to the BO and let them know you'd like to lease your horse out to help with the financial aspect. You or your parents need to be present for this conversation. If the BO freaks out about it, move the horse immediately. If they are supportive of it, then make sure you have a solid contract if the BO decides to lease the horse as a lesson horse, or if an individual rider wants to lease the horse. At the end of the day, you have to protect yourself, your horse, and your financial interests.
Strength is not defined by physical ability. It is determined by your actions and the compassion of your soul.