Tell him you can't go out with him as you are already attached.
When you next meet him to pay rent, bring a bf along....but pls
bring a mature-looking one, not those who looks like a kid.

But best is to not move in, but find another place....seriously,
bec he is so unprofessional. What if he turns out to be a pervert,
and then go into your room when you're not at home?