I don't see any purpose in going to a meeting to confront any still believing Jehovah's Witness. At one time we were just as they are: convinced we had "the truth" and brainwashed to believe any so called apostate was mentally deranged and bitter. Showing up to disrupt a meeting would simply convince me that the Watchtower was right about apostates, and so must be right about everything else. You will not jar anyone's faith, you will just simply confirm it
So, what is the point? To hurt current believing JWs? Do you not remember when you were a believer? Do you think hurting them will prove anything or make you feel better? It won't. Direct your anger to the Watchtower, not individual congregations or individuals. Or better yet, get over your anger, it's better for you anyway to not be bitter and angry.
There are many ways to protest what the Watchtower is doing. Contact local media, start up a petition, post on media reports about Jws, post on Facebook, write your congressman, write to the editor of your local newspaper. But don't walk into the kingdom hall and act like a jerk and expect me to praise you for it.