What should I do with this colleague-he consoled me and leaked the words against me?

was being targeted by some vindictive people indirectly. My colleague and I were Harry potter fans so he compared those people to Voldemort and Death Eaters. He told me to laugh it off. After few days ped, I see the Death Eater = 1 of those vindictive persons, on office whiteboard. Should I confront my colleague and asked him why he did that? How to handle this? I am unable to ignore this. Please help!