My Stepdaughter Must Only Eat Vegan — My House, My Rules

In our vegan household, my 15-year-old stepdaughter demanded meat, rejecting my rules. I told her to stay at her mom’s if she didn’t like it, but she just smiled, and my husband stayed silent. At 2 a.m., I woke to his scream from our 7-year-old son’s room. I found our son, severely allergic to peanuts, sick on the floor, covered in chocolate from a peanut-laced cake. My stepdaughter had given it to him to “teach us a lesson” and fled. I used an EpiPen, and he recovered, but I was livid. I told my husband I never wanted to see his daughter again. He defended her, saying she’s just a teenager who didn’t grasp the gravity of her actions and urged me to forgive her after he spoke with her. I can’t.
This wasn’t a prank—it was dangerous and deliberate. Her resentment over our vegan lifestyle doesn’t justify endangering a child. Trust is broken, and forgiveness feels impossible when my son’s safety is at stake. I need space and boundaries, but my husband’s plea for leniency complicates things. How do I protect my son while navigating this family divide?