De truth

"Defuse" and "diffuse" are not the same word. "Diffuse," which comes from the past participle of the Latin "diffundere" (to spread out), is most properly an adjective and describes something that is not localized, organized or specific; generally a speech or an idea. Diffuse is sometimes used as a verb meaning to scatter--as in light particles--but I advise against it because you are almost certainly going to get it wrong.

Most people say "diffuse" when they really mean "defuse," which means to make less harmful, specifically to make a bomb or a mine inactive. So you defuse a tense and/or dangerous situation, you don't diffuse it.

But you don't need to know all this Latin root stuff (although it helps); you can just look it up in the dictionary. When you don't know what a word means you can look in the dictionary and with the exception of the latest slang and jargon, it will tell you what the word means and even give you an example of proper usage. Don't just keep saying a word because your supervisor does. Because she doesn't know shit.

How doth the little bee improve the shining hour

When someone tells you how miserable they are, resist the temptation to remind them of their blessings. It might cause them to bite you.