What would you do?

Okay so I started dating this guy about a year ago. Wonderful guy. He's very loyal, treats me great, and he's always there for me. We both have kids from previous relationships. Everyone gets along well. I have only been to his house twice In a year. We always stay at my house... I've been labeled a "neat freak" before and I like to live in a clean house. Problem is this guy is a slob. And when I say slob- I mean he lives like a pig. Dishes everywhere for weeks that aren't clean, left over food, his cat litter is hardly ever changed. His bathrooms are beyond filthy. It's just gross really. He has a son that's an adult ( but special needs) very minor but still special - who lives with him and he doesn't clean up either and it just makes it worse.. he never vacuums and honestly the shower is so dirty I'd never shower in there myself... what would you do? I've tried to offer help to him but he's not having it. He just wants to focus all his time on our relationship and that's it. He doesn't care about having his house cleaned at all. His car is even worse. Ugh. He plans to just get rid of everything and move into my house.. but I'm scared it would be the same thing at my house and then I'd be left unhappy. What should I do?!?