Someone I'm seeing is spreading rumours about me, or rather his friend is...

Someone i’ve been seeing for a week is already ruining my reputation.
I just split up with someone, and was looking to get my confidence back, you could say, or just to help get over the other person so I started seeing someone new (someone I have known for years). But only a week later, he has told his friends. One in particular has posted rumours about me on social networking sites, very crude things about my sex life and how much of a whore I am, and how I f*** around.
He doesnt know that I’ve seen what his friend wrote, because it was taken down soon after, but now I need to find the best way to deal with the situation.
Should I call him up and get mad? Completely cut off contact without explanation, in an attempt to rise above it? Or set about getting revenge, like making him book a hotel room, and tying him to the bed and taking pics to post online? That was one idea I’ve had lol.
General smart comments to use would also be appreciated, thank you.