Was this person rude to me, should I have said something back?

So I was in cl and the subject of how hard is the cl was brought up by the professor; I said: "I think the cl is too easy, you should double the amount of work." Then my clmate who I talk to said: "I think you forgot to take your medication." Another person who I don't like (because he is a jealous prick who is jealous of high achievers and always talks crap, but there will always be those type of "people" in this world. He always think he's so tough.) He said: "I think he should go to sleep." Was that a threat? What do you think he meant? Was he just in saying that when I was exercising my freedom of speech? Granted, I know he was exercising his rights too, but I feel insulted. What do you think? I'm really nice and lots of people like me. I ignored the lowlife. Did I do the right thing? What would you have done? It's just so sad that lowlives get to breath the same air successful people do.