long story short, they were never your friends, they are spoiled kids who wanted a toy and they started using you as one. You were a constant source of entertainment to them, by their actions, its pretty much clear that if you involve their parents, things will probably get better, but they will of-course get worse before they get better. What i don't understand is, you went through abuse for so many years, even your parents know about it, and not once did they step up to talk to someone?
Being rich doesn't automatically mean that they are powerful, record these calls, and don't do anything else, continue going to parents of the "chairmen", since you have been to their houses, it would be easier to locate their fathers.
Once you do this, it will frustrate them and they will call, scream, curse and threat, BINGO, you have your evidence, straight away get an FIR