James pretends he doesn't remember what he did, he keeps trying to trick himself, but he knows the truth. It's obvious when Maria says "you were supposed to take care of me". He remembers what happened the last time he had to take care of someone, and pulls away nervously and avoids eye contact. His reaction looks like a mix of guilt and denial.
Luke Roberts (James' actor) said in an interview that in the opening scene James has an episode of psychogenic amnesia, meaning his brain suppressed the traumatic memories. But from his reactions as the game progresses it's obvious the memories come back way before he finally accepts the truth. He knows everything and keeps trying to deny what happened.
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