You're blaming the wrong villain. Joffrey is not to blame for the Red Wedding. It was the work of Tywin, Roose Bolton (the traitor) and Walder Fray. Nonetheless, as a reader of the books I will not spoil anything but I will just say the Lannisters have something coming to them that will blow the entire audience away. In regards to Jack, he is one immensely talented actor and George R R Martin (the author) sent him a message saying "congratulations, everyone hates you" as a joke. However, that statement is very true. I would also like to say that the Red Wedding was very well done in the show. There were a few areas where it differed from the book which may come to haunt the writers, such as the fact that in the book Robb's wife doesn't die and now there is the threat of her returning to the story with the rightful heir to Winterfell. That won't be possible anymore in the show, which I believe is a huge mistake. Also, Martin wrote the Red Wedding chapter in the middle of the third book (A Storm of Swords) but refrained from writing it until the end. It was the last chapter he wrote for the book because when he finished it he broke into tears and he chose not to write anymore chapters for about a year.
