AITA for refusing to comply by my ex-wife’s husband’s rules about what my kids can eat so they can go to their mom’s house?

My ex-wife and I (both in our 30s) divorced 7 years ago. We two boys together aged 8 and 9. My ex-wife remarried two years ago and her husband brought his daughter and son into the marriage. About five months after they got married my ex’s husband sent me a list of foods I could not feed my kids because his daughter is allergic and whenever my boys are at their house his daughter struggles with her allergies. He said he heard it from my kids’ mouths that they eat those things when they’re with me. He said anyone coming into their home needs to avoid those foods. And that I must cut them from my kids diet when they’re at my house, which was every other week at this time.

These include,

Peanut Butter Eggs Cheese Strawberries Chocolate

At first I thought it was a joke but I got an email from this man the next time my kids went to their mom’s house, berating me for not complying with his orders. Then my ex-wife tried to sue me for custody or for it to be placed in the court ordered custody agreement that our boys could not eat those things. She lost the case on both counts. The judge told them they could not decide on what I feed my kids.

So for the past year my ex has not taken her parenting time with our kids. Her husband is not okay with them being there if they’ve eaten those things at my house. He said his daughter could die and even if it’s not that bad, she should not be made uncomfortable because ‘a grown man child with a petty grudge would not comply with keeping a child safe out of spite for the new father in his kids’ lives’.

My ex blames me for her not being a mom to our kids. She told me all I needed to do was follow the list. That everyone has to. And that she’s already had some family members refuse.

Our boys miss their mom but not their mom’s house. I have tried to plan for them to see each other but she won’t lead or drive here. She doesn’t want to see them if they’re not in her house for her custody time. They’re not welcome while they eat those foods. And I’m not depriving them of that stuff because this man orders me to.

I have my boys in custody because of this madness. My ex didn’t handle that too well and she told me I’m being a dick and alienating the kids from her. She told me to follow the rules and let the boys have both of us.

I just want to see what others outside of the equation will think. I have support from others. But these are people who know me. AITA?