If you was in the USA save those text messages... they can possible constitute stalking.

I'd talk with the authorities if I was you. THere are local laws that might apply here. In the USA there definitely is.

Thank god you didn't actually sleep with him... you can now clearly see what sort of scum he really is.

I would talk to someone about what he is doing and also document it. He maybe just bluffung. He sounds like a realt butt-hole and by talking he is showing everyone what a jerk he is. But save the texts show them to someone so you will have someone to back you up. Don't have anything else to do with him.