Try stopping moving immediately when she points the gun at you, and only try moving when she aims the gun elsewhere. If you are experiencing any low framerate or lag in this scene, please try inching up to her slowly.

If you are playing with a gamepad or controller and pull backwards on the stick, it may trigger Brenda to shoot you. Please slowly move forward towards Brenda, making sure to hold the analog stick forward, and immediately release it when she points the gun at you.