Need advice on ettiquette when guests visit my home.?

Let me explain. My in-laws don't sleep together at their own home. We have a fairly large home, but only three rooms are actual "bedrooms." When they come here to visit, my husband insists that we give up two of our rooms which puts us on the couches. Additionally, I am admittedly a germaphobic...I clean like crazy before they come and after they leave. I ask that they use our very large master bathroom, leaving the small guest room for us.....I thought that was generous. But she STILL uses my small bathroom, regardless of my feelings. They are coming again in a week and I have told my husband that they will use ONE bedroom and ONE bathroom and I would make it clear to them. He thinks I'm being ridiculous and selfish. I think he is a momma's boy and it's rude for them to expect to have two of our rooms. (and bathrooms) When we visit them (with our kids), they don't give up anything...they tell us to find room on the couch, the floor, wherever. PLEASE HELP!!!