It's a bit longish, but punctuated correctly.
Correct punctuation does not necessarily make a good sentence. A strict reading would raise the questions, "How is it the suit is carrying a briefcase?" "Is the door telling David about his wife's divorce proceedings, or did the man talk as he was knocking?" These are, of course absurd understandings of your example sentence, but it reminded me of the old joke: "I'll hold this stake and, when I nod my head, you hit it with the hammer."
I suggest something like: David believed he lived (was living?) in paradise until one afternoon a man, wearing a dark suit and carrying a briefcase, knocked at his door to tell him his wife had begun divorce proceedings.
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