I'm sorry for what's taking place. You must live in a non friendly state.
Does your son smoke that you know of? and does he know you smoke if you do?
What did they do to the other kid?
Two year sounds a little harsh hopefully cooler head will prevail, you and your son might have to throw yourself at the mercy of the school board.
Good Luck
Actually I live in one of the most friendliest states in the country which I actually think makes matters worst. As states get more friendly you get the antis such as butt bug making more noise.