This is a classic horror story and is good enough to be included in a professionally published anthology. Readers of course early on suspect that Marlene may have a supernatural quality about her. And, readers are quick to realize that Andy should heed her warning. All the more worrisome when Andy returns to the tree.
You work out the violent scene beautifully. Tension builds, but not too quickly. Great job. (One possible proofreading mistake: "Who are you?” I quiet, high-pitched voice asked". You probably mean A quiet, high-pitched voice)
Thank you for posting this well-constructed story in the Ink Well community. And thank you for engaging with your fellow authors. We are urging everyone who posts in The Ink Well to take this step, going forward, to ensure our community members are supporting one another. (We also have this in The Ink Well community rules on our home page and in our weekly writing prompts.)
RE: The Tree House