Interesting poem, interesting situation. Excellent work, it scans well and sounds good when read out loud.

The attention to the small but telling domestic lapses (no toilet paper, no towels, no salt, etc) is well done. You create a picture/impression of them in just a few words.

The "Dear Reader" usage is very 19th century. In some ways it evokes a memory of Kipling. Which was my first thought after reading the poem. Although it's Kipling as woman, telling a woman's story.

The last line is a BOMB! Just brilliant. It changes everything and makes the reader go back and scan line by line looking for clues.

Suddenly, this isn't a poem about other people's dreary lives and the misery they inflict on themselves. With that line you open a whole new range of meanings to the poem and it becomes less about them and more about you.

Why were you there?

Clearly, she invited you. You wouldn't have gone otherwise. Clearly, you expected dinner and I'm guessing the opportunity to meet her "husband" or "boyfriend". Then things go sideways.

He wanted you to "play" with them. He was hoping for a three-way with her and you. That's what the invitation was always about (at least for him). He pressured her into inviting you and she in "her weakened state, her mental sores" complied.

A "demon" in heat indeed.

Something like this happened to my first wife. A colleague at work invited her over to dinner. The woman's husband turned out to be an abusive brute who was into BDSM.

He had turned his wife into a recruiter for him. He wanted a second slave to sexually abuse and dominate. He saw himself as an "Alpha Male" and basically thought he should have a harem of women to serve his needs.

She told me that his wife (with a doctorate in mathematics) was one of the most "beaten down" women she had ever met. That she lived in terror of his anger and violence at home. That he was always ready to "teach" her a lesson.

Your poem brought that memory back in an instant.

Excellent work.