C'mon, it's his big brother everyone, Gotta give a little consideration. But also cant let him get away with it. alot depends on why he did it. theres the explain method, then the make him suffer method. things easily get blown outta proportion, he does something bad you do something bad back, he calls the cops on you, you plant weed on him or in his house, then he gets arrested, then he burns your house down.. might wanna change your locks and dont let him in. sometimes just cutting ties hurts more than revenge. remember rule #1 don't tell anyone about your grow, he knows so you may need to stop for a while if you think he may snitch on you.
Good luck with this issue, family can suck. but they are still family.