私が怒っていたので彼女は悲しそうだった。

She looked sad because I was angry.

私(わたし)が怒(おこ)っていたので彼女(かのじょ)は悲(かな)しそうだった。

Watashi ga okotteita node kanojo wa kanashisō datta.

私 (わたし、わたくし)

I; me; private affairs; personal matter; secrecy; selfishness

が (が)

indicates sentence subject (occasionally object); indicates possessive (esp. in literary expressions); but; however; still; and

怒る (おこる、いかる)

to get angry; to get mad; to tell someone off; to scold; to be angular; to be square

ので (ので、んで)

that being the case; because of ...; the reason is ....; given that...

彼女 (かのじょ)

she; her; her; girlfriend; sweetheart

は (は)

topic marker particle; indicates contrast with another option (stated or unstated); adds emphasis

だ (だ)

be; is; indicates past or completed action; indicates light imperative

Readings: シ、わたくし、わたし

Meanings: private, I, me

Readings: ド、ヌ、いか.る、おこ.る

Meanings: angry, be offended

Readings: ヒ、かれ、かの、か.の

Meanings: he, that, the

Readings: ジョ、ニョ、ニョウ、おんな、め

Meanings: woman, female

Readings: ヒ、かな.しい、かな.しむ

Meanings: grieve, sad, deplore, regret