He suffocated Mary before her illness could kill her and repressed his memory of doing so.
Daddy was physically and sexually abusive Mommy said she deserved it. Silent Hill 2 offers up these tropes they're waiting for you: The game also has Multiple Endings based on James' general behavior throughout the story (rather than on specific choices at certain junctions).
Often regarded as not only the apex of the Silent Hill series but a masterwork of horror video games, Silent Hill 2 is well-known for its bleak atmosphere and intensely psychological and metaphorical storyline, alongside its much-improved gameplay compared to the original.