Very interesting comments, and I can't disagree with any of them, though it's a while since I've seriously pondered anything about Brideshead Revisited other than the interesting attractions of Sebastian and the quality of his teddy bear.

I do find that tragedy, rightly done, is not depressing. It's a revelation, maybe a catharsis. It's all part of a universal balance, perhaps.

Do it wrong and it's wallowing, but that's probaby more of a function of artistic quality than of philosophy - when wisdom misses the mark, it's trite and meaningless.