Learn Croatian: Nismo se ljutili.

Short words that don't have their own stress, like the reflexive pronoun se, are called clitics. In Croatian, clitics strongly prefer the "second position" in a sentence. Since Nismo is a stressed word, it takes the first spot, and se immediately follows it to take the second position, pushing the main verb ljutili to the end.

Why does the Croatian sentence use nismo (we are not) when the English translation is in the past tense ("were not")?

To talk about the past in Croatian, you use a helper verb (the present tense of "to be") plus an action word called an L-participle. Here, nismo acts as the negative helper verb, and ljutili is the participle. Together, they create the past tense "we were not angry."

Why do we need se here? Doesn't ljutili already mean "angry"?

In Croatian, the verb for being angry is reflexive: ljutiti se (literally "to anger oneself"). If you drop the se, the verb ljutiti means "to make someone else angry." You need se to show that you were the ones experiencing the emotion.

If a group of women were saying this, would the sentence change?