This may be a brave step putting this in here, but here we go...
I have 2DC and 2DSDC. The DSC's have arrived today for their usual weekend with us. My only problem is that I have ben ill since Christmas Day evening with D&V bug. I stopped vomiting yesterday, but have been seriously unwell. (unable to look after my own DC's).
I knew my DH was getting ill earlier and was dismayed that he chose to ignore it. I think it would have been sensible to at least discuss delaying their visit. He had to get me out of bed to help him. That is ok, we are both parents and have to look after our kids. However, he now has his head in a bucket and being sick. He is very unwell.
About an hour ago I asked him to text DSC's mum and say that they needed to be collected tomorrow morning. I think she needs to know. After a little text conversation he has said, could she collect tomorrow unless he sends a message that all is ok. He has said to me that he might feel better in the morning. 
Now DC2 is already ill (not Sick) and very clingy. I will need to be up tomorrow to look after all 4 now, which is going to be hard. But I really think this is unfair on DSC. DH and I have a very nasty bug and DC2 is already harbouring something. Other family members have already caught my bug, so I don't think being around us is fair. I understand their mum needs a break and will have made plans. But AIBU to think they need to go home tomorrow?