Illnesses that come home

So i have two step kids who come here a few times a week. Is it wrong of me being pregnant, and hate when they're "sick" and come to our house? He has to be working to not only pay for our life expenses but also hold support. His ex works a part time job, truly relies on my husband. Anyways, I have had a rough pregnancy being very sick, currently have either the flu or a severe head cold...his two are certainly old enough to know to wash hands, use tissues ect and yet they don't because they aren't made too with mom. They sneeze and cough without covering, bath maybe a few times a week(they are pre teen age) My kid is 5 and knows better! They are supposed to be with us all of the break coming up and I'm having anxiety over the sickness and cleanliness. What do I do? I'm not looking for rude comments....I can't stand the smell of cleaning products so my husband does it once a week while i'm at the dr...like I said it's already been rough with hyperemises, whatever I have now, early contractions:( I'm 28 weeks