[the_logos]

Yup, that's a good start, as is Mabus's suggestion. Another simple, cost-effective "ounce of prevention" is to require players to agree to a Terms of Service that specifically prohibits behaviors you might be worried about and which requires the player to state that he or she is over X age (over 13 if you're collecting personal info in the US, at minimum, but for the OP's game sounds like he's ok with over 16 or over 18.)

Again, as Threshold said, the risk is really very low for a hobbyist (or even a commercial) text MUD but there are cheap ways to reduce your risk even further, so why not avail yourself of them.