How to refuse a playdate

[bobtheunfortunateone]

Two of my children have gone quite often to a friends house for play dates. I have recently found out the mum and her partner do home made porn. All the school knows and I have just found out. She keeps asking when they can come over again and I am running out of excuses. How to deal with it? What to say (carnt let them go cos feel queezy that they film it on there living room sofa ) but her children are friends with mine,