Desperate. I was charged with theft, beaten . Unfair treatment?

You don't say who hit you the cop or a parent? Who is "he"? By the way, I believe the lady. I think you stole the bag and got what you deserved therefore the treatment was not unfair, it is exactly what you deserved. If it was your parent that hit you for stealing you can call family services and charge them. Then Family Service will take you out of the house and either put you in a foster or group home somewhere. That will probably make everyone happy. You should do it.