A little bit of a spoiler
Sorry for the late reply but to get the second ending :
Firstly, when u read the three little pigs story to mint and he asks you the meaning of it pick the first or second option but not the third option (don't pick the ''never spare intruders'' option)
After that, when you kill the girl in the bathroom, don't let mint see the body but instead just hide the body in Magnolias room under her bed (Her room is the room right next to the bathroom) Make sure that Mint does not see the body.
Lastly, just continue playing the game as normal and you will get the second ending. If you need help with the 3 digit door code its 313 (This is the code for the basement)
Sorry for any grammatical problems in this and I hope this helped you!!