Good Comeback?

I just found out a friend of mine, whom I will be calling K, has been body shamed and been called ugly by some other girl B. I was really pissed so me and K devised a plan where I would hate on K and I would try to see how B would reply. B of course hated on K and I sent the messages to K. K feels satisfied knowing that she has the messages but now wants me to block B. I wanna say something snarky to B before I block her, something to confuse her cause I've been pretending to be on her side this whole time. What should I say?