"The Celebration" is so real, it addresses the issues of male childhood sexual abuse so well, I highly recommend it-but prepare for it with support, time, and whatever else you need to take care of yourself.
The curse of movie marketing, I had to search IMDB to find out that The Celebration kept its original name in the UK (Festen). Will look about for the next showing on TV or a sale DVD price, there's no hurry to see it being a movie.
Mystic River on the other hand, I watched without the Oscar hype and the intro to the film is economic, doesn't waste a word or a shot, yet conveys the effect of CSA very effectively and like Sleepers, the kids in the intro acted almost as well as Robbins and Penn later on.