well it was disgusting and very Adam - like. Ealier, he had fallen to the ground with grief and sorrow at his brother's grave. He swore that if he were to go on living, he'd have to confess.
Then Annie decided to tell Adam that she's pregnant. Next thing you see is Adam, in an entirely different mood, at Stuart's grave, cavalierly telling Stuart that in order to save his family, he won't be able to confess, so, as he threw out, "my secret's buried with you!"
<-----I'M TOTES ROLLING MY EYES