Sorry but l don’t agree with saying a child is sick. I would always worry that would really happen if l said that. Make it a relative you don’t care about.
I don't agree with an excuse of any sort, a straight up I'm no longer happy to go due to your behaviour or actions is always my choice. These guys need to be told it's their behaviour that is the issue, why let them get away with it by making an excuse that it's our problem