How can I stop trying to show people reality?

When some idiot tells me to "cheer up" (more useless unsolicited advice, just words without meaning) I wanna dislocate their jaw. I usually just let them have it with words but because of the mindlessness of most people they don't get even a sliver of a clue about what I'm saying. Then I just keep the anger inside and I just want to scream. How can I learn to forgive others' ignorance instead of trying to make them open the eyes they've willfully closed?