How does Ralph betray himself in the Lord of the Flies?

In Lord of the Flies, Ralph betrays himself quite often throughout the novel.  This can be representative of the fact that he is struggling with how he should behave when the pressures of civilization are still weighing very heavily on him, and at the same time, so are the freedoms of their new life on the island. The first instance of Ralph's betrayal of himself occurs in chapter 4 when Jack smacks the glasses off of Piggy's face.  This is completely inappropriate behavior, and yet the boys think this is very funny. Ralph, representing the grown up, civilized authority on the island, does not want to laugh, but betrays himself when he smiles anyway.  

Piggy and the parody were so funny that the hunters began to laugh. Jack felt encouraged. He went on scrambling and the laughter rose to a gale of hysteria. Unwillingly Ralph felt his lips twitch; he was angry with himself for giving way.

The fact that Ralph feels anger at himself for giving way tells the reader that he did not simply break from anger into amusement, but rather he felt anger at Jack's behavior and amusement at Jack's behavior simultaneously.  This inner conflict indicates his betrayal of himself.