As an owner, the best punishment for these people and businesses is simply what you have done-walk away. Without customers, they cannot be an organization that is ethically challenged and morally bankrupt. I'm trying to read between the lines of everything said, but is they are coaches/owners that have stolen money, they won't have money to steal next year, or anyone to spread their lies to. Although it is unfortunate you have to be one of the victims, it has to happen for people to get to the truth and see them for what they are.
Obviously you are not the first to leave, and won't be the last. If what I'm hearing is correct, I'm sure they will not have a gym next year. There have been many gyms closed for much worse, and naturally the bad seeds find their way out. It is not just cheerleading, but all business.