Bu yalan beni gerçekten üzdü.

Because beni is the accusative form of ben (I / me).

• ben = I
• beni = me (as a direct object)

In this sentence, the lie is doing something to me, so Turkish uses the object form:

• Bu yalan beni üzdü. = This lie upset me.

Using ben here would be ungrammatical.

Üzdü comes from the verb üzmek, which means to upset, to sadden, or to make someone feel hurt/sad.

Breaking it down:

• üz- = verb stem
• -dü = past tense ending

So üzdü means:

• he/she/it upset
• made (someone) sad
• hurt (someone emotionally)

In this sentence, the subject is Bu yalan (This lie), so:

• Bu yalan beni üzdü. = This lie upset me.

Because Turkish usually does not use separate subject pronouns unless they are needed for emphasis.

In English, you say:

• It upset me.

In Turkish, the subject is already stated as Bu yalan (This lie), so there is no need for a separate it.

Turkish simply says:

• Bu yalan beni üzdü.

That already contains the subject.

Gerçekten means really, truly, or genuinely.

Here it strengthens the emotion:

• Bu yalan beni üzdü. = This lie upset me.
• Bu yalan beni gerçekten üzdü. = This lie really upset me.

It works as an adverb modifying the verb üzdü.

Yes. Turkish word order is flexible, although some positions sound more neutral than others.

The sentence:

• Bu yalan beni gerçekten üzdü.

is natural and neutral.

You may also hear:

• Bu yalan gerçekten beni üzdü.
• Gerçekten bu yalan beni üzdü.

These can all be grammatical, but the emphasis changes slightly.

A useful general idea:

• the word closest to the verb often gets stronger focus
• the verb usually comes at the end in a neutral statement

So beni gerçekten üzdü sounds like really upset me, with gerçekten closely tied to the action.

Turkish does not have articles like English a/an and the.

So:

• yalan can mean lie, a lie, or the lie, depending on context
• bu yalan means this lie

The word bu already makes it definite and specific, so no article is needed.

This is because of vowel harmony and consonant harmony in Turkish.

The past tense suffix has several forms:

• -di
• -dı
• -dü
• -du
• and their voiceless versions -ti, -tı, -tü, -tu

The verb stem here is üz-. The last vowel is ü, so the suffix becomes -dü.

That is why:

• üzmek → üzdü

This is a very common Turkish pattern.

Usually, yes, when it means to upset someone.

The structure is:

• X, Y’yi üzdü = X upset Y

Examples:

• Sözleri beni üzdü. = His/Her words upset me.
• Bu haber onu üzdü. = This news upset him/her.

The person affected is the direct object, so Turkish uses the accusative:

• beni
• seni
• onu
• bizi
• sizi
• onları

The dictionary form is ben.

Here is the change:

• ben = I
• beni = me (direct object)

This is not something you would usually look up under beni in a dictionary; you would look up ben.

Yes. Üzmek covers a range of emotional meanings, including:

• to upset
• to sadden
• to hurt emotionally
• to make someone feel bad

So depending on context, Bu yalan beni gerçekten üzdü. could be understood as:

• This lie really upset me.
• This lie really made me sad.
• This lie really hurt me.

Upset is often the most natural general translation, but the emotional tone can vary.

Because Turkish normally prefers subject–object–verb order.

Here:

• Bu yalan = subject
• beni = object
• gerçekten = adverb
• üzdü = verb

So the sentence follows a common Turkish pattern:

• Bu yalan beni gerçekten üzdü.

English usually puts the verb earlier:

• This lie really upset me.

Turkish often saves the main verb for the end.