future serial killer

Yesterday I overheard a lovely conversation between two of my co-workers yesterday, one of which is a dumbass married guy (MG) who keeps emailing me. The other guy was telling MG that a neighborhood cat had been crapping in his lawn to which MG responded, "Just put out a bowl of antifreeze, no more cat problem!" So I emailed MG and said he should watch what he says at work, that I had a cat die of antifreeze poisoining and that it is a terrible way to watch a pet die. He wrote me back and "apologized" but said something snarky about how I hadn't responded to an earlier email from him. I wrote him back and said I don't care to be friends with someone who thinks poisoning animals is funny. To which he replied, "I never said it was funny." People like him scare me very much.