You should speak with an attorney. You may well have a legal claim. Parents are generally financially responsible for the intentional wrongful acts of their children; parents are also often resonsible or liable for negligent supervision of their children, if there was any reason to know of a risk the child posed; and it is also possible that the cover up may give rise to further liability, if the cover  up itself caused injury to your child (e.g. allowed more molestation to occur, or delayed medical treatment). Therefore, for there are several potential grounds for liability.