Preschooler With a Nut Allergy - Advice Needed

Hello!TL;DR: Preschool is supposedly nut free, parents have been sending nut laden snacks for 3 weeks before the teachers noticed.So as the title states my 4 year old has a severe allergy to tree nuts. He started school about 3 weeks ago. When we enrolled him we were assured that the classroom is nut free, they do not provide the snacks and snacks from home must also be nut free.Yesterday when I picked him up after his half day session the teacher handed out slips reminding parents to not bring snacks with peanuts/tree nuts. Then TWO of the mothers openly asked "Are pecans tree nuts?" and "Is it ok to send almonds?" I get it, I'm a tree nut allergen mom, I'm more familiar. But they knew immediately that these two things were nuts and had been sending them anyway! One of these moms even substitutes for teachers at this school.Needless to say I'm very worried now. I already had my reservations sending him because of his allergy and risk of exposure but sent him anyway because of the reassurances. At the back to school open house we asked how we leave an epi pen for him and were told we had to talk to the nurse. Talked to the nurse and the preschool isn't part of the school she's allowed to oversee, it's up the the director of the preschool (you know, the one who sent us to the nurse).My son knows not to ever share his food or take food from others unless I say it is ok. But he's 4, and 4 year olds sometimes can be unpredictable. That's a heavy load to put just on him.I want to withdraw him, I want to take this to the principal also, but I've emailed the director asking what steps she plans to take to ensure this doesn't happen again, hoping to resolve this.Am I overreacting? TIA via /r/Parenting https://ift.tt/2PRM9el