How do you justisfy Brutus's act in Julius Caesar?

Brutus loves Caesar, but he is beginning to fear that his
ambition is growing. For this reason, Brutus is justified in his decision to join the
conspirators to murder Caesar. Caesar is becoming more powerful. Brutus would not have
it so. Brutus is disturbed by Caesar’s growing ambition. He fears that Caesar will crown
himself king. Cassius notices that Brutus seems to be troubled about something. He and
Brutus have a private conversation. Brutus states that he is annoyed or upset, but he
does not at first state what his annoyance is. He only states that he at war with
himself:

I’m
annoyed lately
With different passions,
Ideas that only I can
know,
Which are perhaps seen in my behavior;
But don’t let my good
friends be upset—
Cassius, you’re one of them—
Or try to understand
my indifference any further
Than that poor Brutus, at war with
himself,
Forgets to show friendship to other
men.

Brutus is at war with
himself because he fears Caesar will crown himself king. He does not desire for Caesar
to be king. He fears that all Romans will become slaves to Caesar. When the people are
shouting, Brutus fears that the people will have Caesar to become
king:

What
does this shouting mean? I’m afraid the people
Are going to choose Caesar for
their king.

Cassius asks
Brutus a question. Would you not have it so? Would you not have Caesar crown himself
king is Cassius' question. Brutus responds that he would not like to see Caesar crowned
as king:

I
wouldn’t, Cassius; but I really like him,
But why are you keeping me here so
long?
What do you want to tell me?
If it’s anything for the common
good,
Put honor in one of my eyes and death in the other
And I’ll
look on both equally;
Because, let the gods strike me dead, I
love
The name of honor more than I’m afraid
death.

Brutus is an honorable
man. He is well respected. He would not be thinking about joining a conspiracy if he
were not afraid that Caesar has become overly
ambitious.

Brutus does care about Caesar, but he would not
have him to become too powerful. Brutus is justified in in his fears. He is justified in
his thinking that Caesar has become overly ambitious. Brutus is justified in his
decision to kill Caesar because he is protecting the good of Rome. If Caesar becomes
king, all of Rome will suffer. Brutus realizes that he cannot allow his country land to
suffer at the hand of Caesar who has become selfishly
ambitious.

Brutus loves Rome more than he loves Caesar. For
this reason, he is justified in his decision to kill Caesar and rid Rome of Caesar's
tyranny.